Could not find an English wiki for this game, so I wrote my own.
Most of the actions in-game doesn't have proper descriptions for the cost/outcome, so this guide will help you learn what are the costs/outcomes for each actions.

Also, I record the outcomes from my own observations and I might have bought items/skills to increase the stats gain, so there might be some slight error in numbers stated. But please let me know if you find any errors so I can fix it.

Please download the free restoration patch from the Kagura Games official website (just google it) to unlock everything (especially the R18 stuffs) the game has to offer.

After installing the DLC, you have to install the new DLC patch as well.
Some of the DLC parts is still WIP, so be patient as I update bits and parts here and there.

Energy - Energy to do activities (upgradeable up to 120)
Stamina - Stamina to xxx (upgradeable up to 9)
Lust (BLust) - Horny level required to do sexual activities. Max at 120.
Money - Perform Community Service or do Missions to increase salary.
Condition (Cond) - Better condition gives bonus stats gained from training.

• Excellent (+1 bonus from training)
  
• Amazing
  
• Great
  
• Normal
  
• Bad
  
• Horrible
  
• Wounded

Trust - Increase chance of suggestive actions and less likely to wake up at night.
Interest - Increase chance of accepting sexual actions.
Lust (SLust) - Increase chance to masturbate or initiate/accept sexual actions. Max at 120.
Mood - Increase chance of successful interactions and giving gratitude(gifts).

• I Love You
  
• Happy
  
• Normal
  
• Unhappy
  
• Ready to Explode

Note: Don’t go below ‘Ready to Explode’ or the game will be over.

Pat sister on the head to get her sleepier during night activities.

• Deep Sleep (require Sleep Tea)
  
• Heavy Sleep
  
• Normal Sleep
  
• Half Sleep
  
• Half Awake [DLC]
  
• Awake

• Doggy Style - Read Naughty Book
  
• Piledriver - Wash sister’s body when she’s sick. Do it 2 times.
  
• Sixty-Nine - During nighttime, select Fap while Sister is looking at you.
  
• Cowgirl - Own Naughty or Thin Book in inventory and wait for an event at home(RNG).
  
• Titjob - Read Thin Book

Reputation (Rep) - Guild Reputation, affect weekly pay and items sold at stores.
ATK (Attack) - Damage
SKI (Skill) - Crit chance
DEF (Defense) - Defense
DET (Determination) - Block or Dodge
INT (Intelligence) - Special skills activation rate
SP - Skill point for upgrades

Note: Combat stats upgradeable up to 400. Limit break up to 500 after the Hot Spring event.

I would say it’s a hidden mechanic where it’s stated obscurely in the game but it affects your relationship with your little sister and whether she will initiate certain sexual activities on you.

• Normal siblings - pure siblings bond.
  
• Normal but curious - pure siblings bond but started exploring sex on their own.
  
• Curious and awkward - “accidentally” discovered each other's curiosities.
  
• Openly curious - started exploring each other’s desires consensually.
  
• Sexually open - able to initiate/accept sexual advances.
  
• Degenerates - will do anything to satisfy sexual desires.

This is just from my experiments and observations, so it’s not an actual linear progression. For example, you can stay as normal siblings but if your little sister Interest is high enough and your night attack didn’t anger her and she asked you to keep going, it means you will be in the “Sexually open” stage and regarded as a consensual relationship (regardless penetration).
The “Let’s have sex!” command is only available in the “Sexually open” stage.

Another example, I was in the “Normal but curious” stage. Little sister reached Interest 150, so I asked her to wash my xxx in the bath for the first time, which made us in the “Openly curious” stage. From then onwards, she would sometimes give me her used panties as gratitude, even though I never stole any panties before. Also, she would initiate the Cowgirl position at night in this stage or above, not before.

• Basic Training (Max Energy+2, DET+, Energy-35)
  
• Attack Training (ATK+9, SKI+3, Energy-35)
  
• Defense Training (DEF+9, DET+3, Energy-35)
  
• Special Training (DET++, Energy-)
  
• Study Group (INT+12, SP+7, Energy-20)
  
• Help with the Tavern (Gold+250/+350, SP+, Energy-25)
  
• Community Service (Rep+, SP+, Energy-40)
  
• Hunt Mission (Rep+, ATK+2, SKI+2, DEF+2, SP+10, Energy-35)

Note: Prioritize Defense Training as much as you can as DEF can only be increased from weekday activity.

Learn Chef skill for chance on delicious cooking (Energy+5, Mood+)

• Little sister homecook meal (30min, Money-100, Energy+20, Cond+)
  
  • I’m more horny than hungry! [DLC] (req BLust 100, SLust 40, Interest 100, consensual sex) (BLust-40, SLust-30)
    
  • Nah, I'm starving [DLC]
• Leave it to me (60min, Money-100, Trust+2, Energy+15, SP+1, Cond-)
  
  • At BLust 100, option to add “special ingredient” (Interest+2, SLust+10, BLust-60)
• We’re eating outside (30min, Money-300, Energy+20, Mood++, Cond++)
  
  • Let's dig in!
    
  • Show me your tits (req Interest 150)
    
    • At SLust 60, she drops her spoon. [DLC] (BLust+15, SLust+20)

Buy Dumbbell and Iron Sandals to increase stats gain by +1 each.

• Muscle training (ATK+2/+5, Energy-20)
  
• Practice swing (SKI+2/+5, Energy-20)
  
• Meditation (INT+2/+5, Energy-10)

If you own either Naughty book or Thin book, there will be random event where sister found the book while rearranging shelves. (Cond-, Cowgirl skill)

• Children book (INT+2)
  
• Serious book (Interest-1, INT+3, SP+1, BLust-20)
  
• Adventure book (All Combat Stats+2)
  
• Naughty book (Trust-1, Interest+5, SLust+15, BLust+5, Doggy Style Skill)
  
• Thin book (Trust+1, Interest+8, SLust+16, BLust+6, Titjob Skill)
  
• Memories Album [DLC] - CG Gallery

Naughty Touch skill will add additional SLust+5.

• Head pat (Mood+)
  
• Shoulder massage (Trust+1, SLust+3/+8, BLust+3) (req Trust 50)
  
• Hug [DLC] (Trust+1, SLust+4, BLust+4) (req Trust 50)
  
• Kiss [DLC] (Trust+1, SLust+5, BLust+4) (req Trust 100)
  
• Tickle (Interest+1, SLust+8/+13, BLust+5) (req Trust 100, Mood Happy)
  
• Molest
  
  • Show me your panties (SLust+6, BLust+7) (req Interest 50)
    
    • Keep going [DLC] (BLust+5 then BLust+7) (req Interest 250)
      
    • That's enough [DLC]
  • Show me your body (Interest+1, SLust+20, BLust+10) (req Interest 100)
    
    • Keep going [DLC] (BLust+15) (req Interest 300)
      
    • That's enough [DLC]
  • Let me watch you masturbate [DLC] (BLust+25, SLust-20) (req Interest 200?, SLust 50)
    
  • Watch me masturbate [DLC] (Interest+4, BLust-22, SLust+20) (req Interest 150, SLust 50?)
    
  • Blow on my xxx (Trust-1, Mood-, Cond+) or (SLust+1, Cond+)

• Conversation
  
  • Goof around (Trust+2)
    
  • Naughty talk (Interest+1, SLust+2)
    
  • Scary talk (SP+2) (Chance on Sis Toilet, Trust-1)
• Blow on (Trust-1, Mood-, Cond+)
  
• Pamper
  
  • Praise her (Mood+)
    
  • Apologize (After you’ve done something bad)
    
  • Have a snack (Mood+, Trust+2) (req Snack)
    
  • Have a present (Mood++, Trust+12) (req Present)

• Peep (Chance on Masturbating if SLust is high)
  
  • Keep watching (BLust+5, Alertness+) (BLust+10 if masturbating)
    
  • Hold your breath (Alertness-)
    
  • Jerk off (BLust-40)
    
  • Pretend to be a cat (Alertness Max/Min chance)
    
  • Escape (Skip) (disabled if BLust is 100. Must Jerk off to end)
  
  
• Hunt for panties (Panty+1, BLust+5)
  
  • Keep looking (Panty+1, BLust+5) (req Panty Hunter)
    
  • Masturbate (BLust-40)
    
  • Sniff them (BLust+10)
    
  • Lick them (BLust+15)
    
  • Put them back (Skip) (disabled if BLust is 100. Must Jerk off to end)
  
  
• Do nothing (Skip)

Require Trust 100 to enter bathroom together.
Require Trust 200 to initiate washing each other.
At Trust 300, little sister will get into the tub with you.

• Get in the bath
  
  • Talk about something
    
    • Goof around (Trust+1)
      
    • Naughty talk (Interest+2, SLust+5) (Interest gain stopped after 100)
  • Offer to wash her (Trust+1, BLust+5)
    
    • Wash her back (Trust+1, BLust+5)
      
    • Masturbate (BLust-40) (req Interest 150)
      
    • XXX her (BLust-40) (req Interest 200)
  • Drink the bathwater (??)
  
  
• Wash up first
  
  • Talk about something
    
    • Goof around (Trust+1)
      
    • Naughty talk (Interest+2, SLust+5) (Interest gain stopped after 100)
  • Wash your hair
    
  • Wash your body (Handjob if SLust 50+, BLust-40/-80) (yes, she will drain you dry)
    
    • I’m fine (Skip)
      
    • My xxx (BLust-40) (req Interest 150)
      
    • XXX her (BLust-40) (req Interest 200) (penetration only if you have done it in bed before)
• That felt good (Skip)

Every drinks will have a chance for toilet break

• Green Tea (Energy+10)
  
• Coffee (Stays up much later)
  
• Black Tea (Energy+5, Stays up late, Mood+)
  
• Sleep Tea (Sis Deep Sleep)
  
• Stimulant (Stamina+2, BLust+30)
  
• Love Potion (SLust+20, Sis Horny)
  
• After Pill (Better safe than sorry. Drink this AFTER the act)
  
• Energy drink (Energy+30)

Require consensual sexual activities done before. Approximate 4 times?
Require BLust 70, SLust 50 and Sis Mood at least Happy.

At BLust 50, initiate late night activity.
Sleep before 21:00 to wake up at 23:00.
Sleep between 21:00-22:00 to wake up at 23:30.
Sleep at 22:00 onwards, add 90 minutes to wake up at night.

• Mess with her
  
  • If not doing anything, auto jerk off before end (BLust-30)
    
  • At Interest 150, you can “Wake her”.
• Adjust her blanket (Fix her blanket)
  
• Call it a day (Skip)
  
  • At BLust 120, have a naughty dream with little sister or other guild girls.
    
  • At Interest 150, SLust 70+ if you have Cowgirl skill, little sister will assault you in said position.

• Peep on her (Chance on Masturbating if SLust is high)
  
  • Peeing (BLust+8)
    
  • Masturbating (BLust+15)
• Walk in (req Interest xx, consensual sex)
  
  • First time
    
    • Yes, I do! Absolutely! (Interest+2, SLust+5)
      
    • If anything, I want to drink it! (?)
      
    • No, I was just joking (Trust-4, Interest+1)
  • Next time
    
    • First time just watching
      
    • In your mouth (BLust-60, SLust+20)
      
    • Inside you [DLC]

• Dream talk (Rep+, SP+14)
  
• Random talk (Trust+6, SP+10)
  
• Naughty talk (Interest+6, SP+10)
  
• Blow on (Trust-1, Interest+4, Mood+, SP+10)

• Walk around the village (Trust+1, Mood+, Cond+, Energy-15)
  
• Town (Money-100, Trust+4, Mood+, Energy-20)
  
• Swimming (Money-500, Trust+8, SP+5, BLust+7, Energy-30)
  
  • Have sex (req consensual sex)
    
    • ♥♥♥ inside
      
    • ♥♥♥ outside
  • Play in the river
• Ocean (Money-1000, Trust+20, SP+5, Energy-40)
  
  • Call to Sis (BLust-40)
    
  • Call to Yui [DLC]
    
  • Call to Kasumi [DLC]
• Hot Spring (Money-1500, Trust+20, SP+8, Energy-30)
  
• Adventure time! (All Combat Stats+, SP+, depends on progress)
  
  • Proceed (Progress 1 step, Sis Health-1, Energy-5)
    
  • Carry her (Progress 1 step, Energy-8)
    
  • Rest (Sis Health+3, Energy+15)
    
  • Return home (End)

Buy Dumbbell and Iron Sandals to increase stats gain.

• Muscle training (ATK+2)
  
• Practice swing (SKI+2)
  
• Go for a run (DET+1, Max Energy+1)
  
• Study (INT+2)

• Keep looking (BLust+5, Panty+1) (req Panty Hunter)
  
• Stop (Skip)
  
• Masturbate (BLust-50)
  
• Sniff them (BLust+10)
  
• Lick them (BLust+15)
  
• Put them back (Skip)

Money+800/+1000 with Farmer skill

Skip to evening

Can be done 3 times from morning, so minimum BLust 90, SLust 60 to do it 3 times.

• Green Tea (2 for 200G)
  
• Coffee (2 for 200G)
  
• Black Tea (2 for 300G)
  
• Sleep Tea (2 for 800G) (req Town's Only Bar Rep)
  
• Sweets (200G)

• Present (500G)
  
• Soft Pillow (2000G) (Sister sleep deeper) (req Minor Guild Rep)
  
• Feather Mattress (4000G) (Energy Recovery+20) (req Playing Pretend Rep)
  
• Dumbbell (1000G)
  
• Iron Sandals (1000G)
  
• Condom (2 x 200G)

Pajamas are for cosmetics only. No stats bonus. 3000G each.
You can't manually decide what she wear.
Little sister will randomly pick her pajama after every bath.

• Adventure Book (300G/200G)
  
• Naughty Book (500G/300G)
  
• Thin Book (800G/500G)
  
• Counterattack Scroll (4000G/3000G)
  
• Concentration Scroll (4000G/3000G)
  
• Firmness Scroll (4000G/3000G)
  
• Full-Force Strike Scroll (4000G/3000G)
  
• Preemptive Strike Scroll (4000G/3000G)

• Stimulant (400G)
  
• After Pill (1000G)
  
• Vibrator (2000G)
  
• Dildo (4000G) (req Minor Guild Rep)
  
• Anal Dildo (10000G) (req If you know, you know Rep)

• Train offensive (ATK+, SKI+, Energy-35)
  
• Train defensive (DEF+, DET+, Energy-35)
  
• Train special (INT+, SP+, Energy-25)
  
• Just relax (Cond+, Energy+15, beautiful ocean view)
  
  
• Talk about the future (Trust+2, Rep+, SP+10)
  
• Naughty talk (Interest+4, SP+10)
  
• Random talk (Trust+6, SP+10)

How to read: if your current Rep is Total Amateurs, you need Rep+ 4 times to progress to Town's Only Bar and another Rep+ 4 times to progress to Playing Pretend and so on.
Note: the required numbers might be inaccurate, as this is hard to track with no visible counter.

• Totally Obscure - Rep+4
  
• Total Amateurs - Rep+4
  
• Town’s Only Bar - Rep+4
  
• Playing Pretend - Rep+6
  
• Minor Guild - Rep+10
  
• If you know, you know - Rep+4
  
• Local Guild - Rep+6
  
• Mid-Size Guild - Rep+6
  
• The Select Few - capped until after defeating Black Gate
  
• Regional Representative

• Strength - Each point increases ATK, SKI, DEF, DET by 30
  
• Intelligence - Each point increases INT, SP by 40
  
• Loving family - Each point increases Trust by 50
  
• Naughty sister - Each point increases Interest by 50 and SLust by 20
  
• Money - Each point increases Money by 10000
  
• Friends Level - Each point increases party members strengths by ??
  
• Unyielding Flesh (Max Energy+10, Attack+, Defense+, Auto-Heal, Healer)

You can get NG+ points based on the below criteria (max 15 points):

• .5 point each 10 days that have passed, up to a cap of 10 (55 days=5 points, 216 days=10 points)
  
• 1 points for a completing panty collection
  
• 1 points for completing the story
  
• 1 points for clearing the Great Adventure
  
• 1 points for clearing Yukari's favorability event
  
• 1 points for clearing the Food Menu challenge early on in-game
  
• 1 points for clearing the Seal Subjugation event in the alternate branch of the game
  
• 1 points each for reaching LV 5 favor with Kana, Yui, and Kasumi
  
• .5 point for defeating Great Squid (post-game subjugation)
  
• .5 point for defeating Psycho Macho (post-game subjugation)
  
• .5 point for defeating Menhera-chan (post-game subjugation)
  
• .5 point for defeating Silent Killer (post-game subjugation)
  
• .5 point for defeating Seal Heroes (post-game subjugation)
  
• .5 point for Super Adventure Cleared
  
• 1 points for finishing the Onsen Event

Contributed by: FFFox
Note: Check out his awesome Kitsune Imouto mod (can't include link), but you can join Kagura Games discord group and in #living_with_sister_monochrome_fantasy channel, you can find the download link in the pinned message.

WIP need to validate later.

• Day 11 - Exhibition match
  
• Day 15 - Guild bounties
  
• Day 18 - Regional qualifier. Fight Akatsuki. (if win, refer to a)
  
• Day 23 - Akatsuki notify about seal hunt mission
  
• Day 24a - Discussion with Yukari
  
• Day 24b - Discuss with others on how to save the guild. (Learn Chef skill and have Sis cook dinner)
  
• Day 25a - Mock battle
  
• Day 29 - Seal hunt mission (3 days)
  
• Day 33 - Guild decision
  
• Day 46 - Exhibition match
  
• Day 52 - Meet fortune teller
  
• Day 53 - Eights tournament qualifier
  
• Day 54 - Yukari suggest for a training camp
  
• Day 57 - Training Camp Week
  
• Day 64 - Joint mission to slay monsters
  
• Day 74 - Tournament begins
  
• Day 78 - Semifinal
  
• Day 84 - Final
  
• Day 85 - Ruin clearing hunt mission (40-step, 15 days)
  
• Day 95 - Rematch with Akatsuki (if you have completed the 100-step grand adventure and ruin clearing mission only)
  
• Day 100 - Last day before day missions are locked

Requirements:

• Complete main story events
  
• Complete 100-step grand adventure
  
• Akatsuki rematch
  
• Watch first ending credits.

• Day 1 (First Monday) - Yukari announce hot spring trip (for me it happens on day 106)
  
• Day 6 - Hot Spring trip
  
• Day 7 - More monkey battles. Stats limit unlock up to 500.
  
• Day 8 - Day missions are unlocked. Monkey Army hunt mission unlocked.
  
• WIP

WIP I'm still playing/exploring this.

WIP

• Kana practicing a new technique. Help her train. (ATK+5, SKI+5, Energy-20, Kana+)
  
• Kana looking at an expensive sword.
  
• Kana goes hunting to master her technique. Kana learned Fast Slash. Unlock Follow-up.
  
• Kana randomly join for dinner.

• Yui doing running training. Join her. (Max Energy+1, DET+5, Energy-20, Yui+)
  
• Meet Yui at the guild. Treat injury.
  
• Yui got attacked by a boar. Combat.
  
• Yui tripped and fell during training. Learn Emotional Support. Unlock Leader.
  
• Meet Yui in town handling children in restaurant.

• Bump into her in town.
  
• Saw her in the bookstore.
  
• Guild members discuss needing a genius.
  
• Kasumi being attacked by a thug in town.
  
• Meet Kasumi in bookstore (Day 41-42)
  
• Day 43 - Kasumi visited and joined the guild. (Unlock Battle Master skill)
  
• Kasumi watched you having a scuffle with Akatsuki at the guild. She cheers you on.
  
• Play chess with Kasumi at guild. Unlock skill Preparations

• Found food in the guild. Contain yourself. (Trust+1, SP+2, Energy+10)
  
• Yukari asking for help moving stuff in the warehouse.
  
• Yukari setup table at the guild to meet the chief and you call her a hag.
  
• Yukari drinking alcohol.
  
• Akatsuki leaving the guild after inviting Yukari to his guild.

• After Basic training, he’ll challenge you to a running match. (Rep+, DET+1/+2, Energy-10 per turn, Rep+, Physical Stats+4 if you last 3 turn, unlock Iron Body skill)
  
• Meet Akatsuki in town for a ramen battle. Unlocked skill Decisive Battle

• Find a wallet. Report to guild. Get sweets.
  
• Guild house is kind of a mess. Clean up. (Energy-10, SP+2)
  
• Greeted by a traveling doctor. Don’t need it.
  
• Legendary chef Ajiboy. Accept food. (SP+10)
  
• Passed by a blacksmith. Repair sword. (Gold-400)
  
• Day 41-42 - Comic merchant day
  
• Gone to town and eat Saburo Noodle. (DET+3)
  
• Purse Snatcher in town.
  
• Doctor DJ visits home. Very risky, recommended to refuse.
  
• Flower girl selling “flower”.
  
• A bear head dude visit home.
  
• Found a naughty book in the field. Picking it up reduces Rep.

I might add some other information later if I have enough time and energy.
Please let me know if there's a certain parts you would like to be added in here.
Also feel free to reach out to me if you would like to contribute to this guide.

Cheers and Enjoy Brothers!