There are four episodes:

• Episode 1 ends after you encounter Nikki's friends in your home.
  
• Episode 2 begins when you meet Valerie for the first time, and ends after you watch TV series with Nikki.
  
• Episode 3 begins "1 month after you arrive in Isokaze" and ends after the concert.
  
• Episode 4 begins with carving the pumpkins and concludes the game.

Most choices affect the game only slightly and subtly, but sometimes even much farther in the game. However, only few choices are major.

Choices made during episode 1 do not affect your relationships at all. When this guide says that a choice "doesn't matter", it merely means that it doesn't affect what relationship you get into and that it won't get you any additional CG scenes. In particular, the outcomes of all three matches do not matter.

In episode 2, you can choose a primary girl for episode 3. Except for Kaori, this won't affect whether you're able to start a relationship with her, but throughout episode 3, you will be reminded that you are somewhat closer to this girl.

Except for the first episode, the format of the episodes is such that in each episode, you have a certain number of "free time" slots when you can spend time with girls. At the end of each episode, there is an additional event with a single girl or Shou; but to be able to choose a girl at that point, you must have completed all of her "free time interactions" during that episode, plus maybe some additional requirements.

Choices made in Episode 1 do not matter, except that they unlock some minor CG scenes.

Episode 2 (starting with meeting Valerie) consists of five days. Each day, you can spend time with girls in your free time. The first three days, you get 2 time slots per day, but you only get 1 time slot for the last two days:

• Day 1: afternoon, evening (only option to choose Nikki)
  
• Day 2: afternoon, evening
  
• Day 3: afternoon, evening
  
• Day 4: afternoon only
  
• Day 5: afternoon only

You may only spend time with a girl once per day. There are three interactions possible with each girl, and they happen in order. Because there are eight time slots in total, you may "max out" interactions with 2 girls only. Also, not all interactions are not always available. The availability times are these (in order: first interaction, second interaction, third interaction).

• Kaori: afternoon, evening, afternoon
  
• Mayu: afternoon, afternoon, afternoon
  
• Shou: evening, afternoon, evening
  
• Valerie: afternoon, evening, afternoon
  
• Yuuna: evening, afternoon, afternoon

At end of episode 2, just before Nikki tells you about her work on your bike, you may pick a girl with whom you have had all three interactions. Your choice will determine the girl you will be closest to for the duration of episode 3, and will lead into your fourth interaction with the girl, but anything you do during that interaction does not matter.

Exception: For Kaori, in her final (fourth) interaction, when you get to the daycare center, you must pick "Return her groceries." to successfully complete the interaction.

Episode 3 consists of several days:

• Day 1: You have free time.
  
• Day 2: Beach (no choices matter).
  
• Day 3: You have free time.
  
• Day 4: Onna-Bugeisha match (important Kaori choice).
  
• Day 5: You have free time.
  
• Day 6: Romance lock-in day.
  
• Day 7: Concert.

Free time works similarly to episode 2. Time slots are these:

• Day 1: afternoon, evening
  
• Day 3: afternoon, evening
  
• Day 5: afternoon, evening

Again, you may only interact with a girl once per day. Each girl has up to 2 interactions in episode 3. The availability times of these interactions, in order, are these:

• Kaori: day 1 afternoon, day 3 evening
  
• Mayu: any afternoon, any afternoon
  
• Shou: any evening, any afternoon
  
• Valerie: any evening, any evening
  
• Yuuna: any afternoon, any evening

Your choices during these interactions do not matter.

To start a relationship with a girl, you must have completed both of her episode 3 interactions.
Then, at the start of sixth day,

• If you completed 2 episode-3 interactions with Kaori, she will have called you. If you respond "Make sure Kaori is okay.", you are locked into her route, see "Kaori".
  
• If you didn't, or if you choose "She can call me back," you can pick from other girls. However, an option for a girl will be available only if you completed 2 episode-3 interactions with them.

The choices are:

• "I wonder what Yuuna is up to today." - Yuuna
  
• "I have commitments to hang out with Shou and his brother." - Shou
  
• "Let's see what Valerie has planned!" - Valerie
  
• "Is Mayu free to hang out?" - Mayu
  
• "Just sleep in and skip my day." - nonstandard game over

Remember you must have 2 interactions for the choice to show. Also, if you embraced Kaori in episode 3, you cannot establish a relationship with any other girl.

Episode 4 consists of several days:

• Prologue: Pumpkin carving.
  
• Day 1: You have free time.
  
• Day 2: Hot springs
  
• Day 3: You have free time.
  
• Day 4: Match against REBORN.
  
• Day 5: You have free time (also Aluvian interview).
  
• Day 6: Final weekend event.
  
• Day 7: Conclusions.

Free time works similarly to episode 3. Time slots are these:

• Day 1: afternoon, evening
  
• Day 3: afternoon, evening
  
• Day 5: afternoon, evening

Again, you may only interact with a girl once per day. Each girl has up to 2 interactions in episode 4. The availability times of these interactions, in order, are these:

• Kaori: evening, evening
  
• Mayu: afternoon, evening
  
• Shou: afternoon (not on day 1), afternoon
  
• Valerie: evening, afternoon
  
• Yuuna: afternoon, evening

A previous version of this guide said that Shou's second interaction is in the evening. That's incorrect, it is, in fact, in the afternoon.

Your choices during these interactions do not matter.

To access the final event of your chosen route, you must have established a relationship with that girl at the end of Episode 3 and completed both of her Episode 4 interactions.

If there is no such girl, but you completed all of Shou's episode 3 and episode 4 interactions, then you will be able to access Shou's or Nikki's final events.

If not even that, then you will access Nikki's final event.

In episode 3, complete both of her interactions in your free time.
Then, in the final segment of episode 3, choose these when they are available:

• "Let's see what Valerie has planned!"
  
• "Hug her."
  
• "Kiss her."
  
• "Yes."

In episode 4, complete both of Valerie's free time interactions.

If you also interacted with Kaori a lot in episode 3, you must not choose "Make sure Kaori is okay." near the end of episode 3.

In episode 3, complete both of her interactions in your free time.
Then, in the final segment, choose these when they are available:

• "I wonder what Yuuna is up to today."
  
• "Pull her into my arms."
  
• "Yes."

In episode 4, complete both of her free time interactions.

If you also interacted with Kaori a lot in episode 3, you must not choose "Make sure Kaori is okay." near the end of episode 3.

In episode 3, complete both of her interactions in your free time.

Then, in the final segment, when you call with Mayu, you have these options:

• "I like Mayu, but she should be with Shou." This will lead into a "mock date" that will end in romance between you and Mayu.
  
• "No, she should tell Shou how she feels." Same as above.
  
• "Yes, she should be with me instead." Leads into a real date that will end sadly.

If you choose "I like Mayu, but she should be with Shou.", then your mock date will end abruptly, however, just after the concert, Mayu will hand you a letter. When you open it at home, choose these options, in order, to establish your relationship:

• "I feel the same way."
  
• "Yes."

In episode 4, complete both of her free time interactions.

If you also interacted with Kaori a lot in episode 3, you must not choose "Make sure Kaori is okay." near the end of episode 3.

This is the most difficult relationship to establish.

To get into the Kaori route, you must:

• In episode 2, complete 3 interactions with Kaori.
  
• At end of episode 2, choose "Maybe Kaori will show me how she made her delicious bento." just before Nikki shows you into the garage. Then, when you get to the daycare center, choose "Return her groceries."
  
• In episode 3, whenever you have an option to spend free time with Kaori, you must choose it.
  
• When Kaori storms out after the Onna-Bugeisha match, choose these options:
  
  • "I'll go check up on her."
    
  • "Embrace Kaori."
    
  • "Yes."
• At end of episode 3, when you have a missed call from Kaori, choose "Make sure Kaori is okay."

In episode 4, complete both of her free time interactions.

Finally, in the final event of episode 4, when you are in the hotel suite, choose these options:

• "...We can share?"
  
• "FINE, I'LL TAKE THE BED THEN!"

Note: Previously, there was a bug that caused Shou's final event to not trigger. The bug is fixed in the current version of the game.
Note: It is possible that you also need to complete Shou's episode-2 event. I don't think that's necessary, but I'm not sure.

Shou is not romanceable.

However, at the end of episode 4, you will access Shou's final event if the following conditions are met:

• You completed both of Shou's episode-3 interactions.
  
• You chose "I have commitments to hang out with Shou and his brother." to get Shou's event at end of episode 3.
  
• You completed both of Shou's episode-4 interactions.
  
• You choose "Hang out with Shou." (and not "I wonder what Nikki's up to.") at end of episode 4.

Nikki is not romanceable.

However, Nikki does have a final event (maid café). To access this event, also known as the best route, you must not establish any relationship at the end of episode 3.

If you interacted with Shou enough, choose

• "I wonder what Nikki's up to."

at end of episode 4. Otherwise, Nikki's final event will trigger automatically.

A code such as "E1D3" means "episode 1, day 3".

Unmissable CG's
GEAR Eagle
- E1D3 (unmissable)
GEAR Cockpit
- E1D3 (unmissable)
GEAR Overdrive
- E1D4 (unmissable)
GEAR Onna Bugeisha (Kaori v. Mei)
- E3D4 (unmissable)
GEAR Claw of the Wild (tatsuo)
- E2D5 (unmissable)
GEAR Akira
- E4D4 (unmissable)
GEAR Final Clash
- E4D4 (unmissable)
Takeda's Office
- E2D3 (unmissable)
At the Beach
- E3D2 (unmissable)
The Family Photo
- E1D1 (unmissable)
Nikki and Ken
- E3D5 (unmissable)
Nikki in the Park
- E4D1 (unmissable)


Other
GEAR Aludian Poster
- Keep reading after the end of credits.
First Ride With Helmet
- E1D2: "Take the motorcycle"
- E1D2: "Safety first!"/"Helmets are a good accessory."
First Ride Without Helmet
- E1D2: "Take the motorcycle"
- E1D2: "Psh, helmets are for wimps."

Kaori
Kaori at Intersection Hit
- E1D2: "Take the motorcycle"
- E1D2: "GUN IT!"
Kaori Force eating
- Spend time with Kaori in Episode 2 (first interaction).
Kaori Hug
- E3D4: You must take the Kaori route (see Kaori).
Kaori Couch
- E3D6: You must take the Kaori route (see Kaori).
Kaori Kindergarten
- Spend time with Kaori in Episode 4 (first interaction).
Amanda Lee
- This scene happens during Kaori's final episode 4 event.
Kaori Hotel
- This scene happens during Kaori's final episode 4 event.
- "...We can share?"
- "FINE, I'LL TAKE THE BED THEN!"

Valerie
Valerie Broken Heel
- Spend time with Valerie three times in Episode 2.
- E2D6: "Valerie and I should get started on our class project."
Valerie Entrance
- E2D1 (unmissable)
Valerie Kiss
- E3D6: You must take the Valerie route (see Valerie).
Valerie Dinner
- You must have a relationship with Valerie.
- Spend time with Valerie in Episode 4 (second interaction).
Valerie Ferris Wheel
- This scene happens during Valerie's final episode 4 event.

Yuuna
Yuuna Bus Meeting:
- E1D2: "Take the bus"
- E1D2: "Meh, I'll take my chances."
Yuuna Bike Ride
- E1D5: "Work on the history project with Yuuna."
- E1D5: "Offer her a ride."
- E1D5: "Help her."
Yuuna Tennis Match
- Spend time with Yuuna in Episode 2 (first interaction).
Yuuna Cooking Club
- Spend time with Yuuna in Episode 3 (first interaction).
Yuuna Ice Cream
- E3D6: Choose to be with Yuuna at end of Episode 3.
Yuuna Embrace
- E3D6: Establish the relationship with Yuuna (see Yuuna).
Yuuna with Dog
- Spend time with Yuuna in Episode 4 (second interaction).
Yuuna Tent
- This scene happens during Yuuna's final episode 4 event.

Mayu
Mayu Violin Practice
- Spend time with Mayu three times in Episode 2.
- E2D6: "Mayu owes me a violin lesson."
Mayu Shopping
- Spend time with Mayu in Episode 3 (second interaction).
Mayu Confession Letter
- E3D7: Establish a relationship with Mayu (see Mayu).
Mayu Date
- You must be on the Mayu route (via a mock date, see Mayu).
- Spend time with Mayu in Episode 4 (second interaction).
Mayu Motel
- This scene happens during Mayu's final episode 4 event.

A full narrative graph of ACE Academy is here:

http://i.imgur.com/aZ3hSAG.png

The graph is extracted from the decompiled game files. In theory, this should not be done, but it's such a common thing in the visual novel world and with ren'py especially that I hope the developers won't mind.

It's big - I recommend you download it and view it in an image viewer on your computer, not directly in your browser (Chrome doesn't support images this big very well, at least).