There is a Guide from the Japanese version of this game on the Internet from the user "elf3460", but I have translated this from Latarus's Russian version who gave him credit for it.

Private

• Starter rank that allows you to go on patrols.

Sergeant

• Now you need to collect only 8 "Checkpoint".
  
• You can conduct a search on the first floor of the "Dungeon".

Lieutenant

• Now you can run during patrol.
  
• You can "talk" with prisoners one-on-one.
  
• It becomes possible to buy items from "Theodore".

Captain

• You can now choose the area to patrol.
  
• You no longer have a timer until the end of the patrol.
  
• You can use all the rooms on the lower floors of the "Dungeon".
  
• The assortment of items at "Theodore" is expanded.

Vice-Commander

• You get the key to the "Dungeon", i.e. now you don't have to pay the guard for it.
  
• The assortment of items at "Theodore" is expanded further.
  
• You get your own room.
  
• Character editor is unlocked.

Salary
Your salary depends on two factors; what rank you have & what time of day you go on patrol.

Private - Day (500) & Night (-)
Sergeant - Day (750) & Night (900)
Lieutenant - Day (1,000) & Night (1,200)
Captain - Day (2,000) & Night (2,400)
Vice-Commander - Day (5,000) & Night (6,000)

Other ways to earn money:

• Bribes for "turning a blind eye" to a crime (the amount of the bribe depends on the area you patrol).
  
  
• Helping girls "in trouble" (taking them to the doctor).
  
  
• Handing over captured girls to the "Houses of Love" (This opportunity opens after receiving the rank of "Vice-Commander" and taking the corresponding tasks from the "Commander").

What to do with money
Money can be spent on purchasing various items from Theodore, visiting Houses of Love, bribing Commanders, and completing quests.

To obtain each rank, you need to collect a certain amount of Promotion. You can get it in the following ways:

• Complete patrols (the amount of Promotion received depends on the rank and time of day):
  
  Private - Day (5) & Night (-)
  Sergeant - Day (10) & Night (15)
  Lieutenant - Day (15) & Night (20)
  Captain - Day (20) & Night (25)
  Vice-Commander (Day (-) & Night (-)
  
  
• For arresting criminals (10 Promotion for each).
  
  
• For defeating criminals (20 Promotion for a standard, 50 Promotion for a strong).
  
  
• For locking girls in cells (This option is on the first floor of the "dungeon" in the right room. For each prisoner, 10 Promotion).
  
  
• Give a bribe to Commander (for 1,000G you will receive 20 Promotion).

• You can meet a "suspicious man" and guess where he hides an illegal item, either arrest him or take his money.
  
  
• You can meet an "ordinary woman" and guess where she hides an illegal item, you can arrest her, take her money or trigger an H-event.
  
  
• You can meet a "priestess of love" and point out the illegality of the service she provides, you can arrest her, take her money or trigger an H-event.
  
  
• You may encounter a "running criminal" who you will need to catch up with to either arrest him or take the money.
  
  
• You may encounter an "attacking criminal" who you will need to defeat, after which you will receive a Promotion and if the criminal was a girl, you will be able to "talk" to her in the detention center.
  
  
• You may encounter a drunk who will simply waste your time.

Theodore range

Lieutenant - Banned Goods.
Captain - Added Sleeping Drug, Pregnancy Drug, Stimulant & Narcotic.
Vice-Commander - Added Ominous Charm & Lucky Charm.

Quests

Upon reaching the rank of "Vice-Commander", you can complete two tasks for the Commander:

• The ability to bring prisoners to your personal room.
  
  To do this, you need to send 10 prisoners with large breasts to the "Houses of Love" (you can send prisoners on the first floor of the "Dungeon" in the right room) and give the Commander 30,000G.

• Increasing the number of cells on the lower floor of the "Dungeon"
  
  To do this, you need to send 20 prisoners to the "Houses of Love", either with large breasts or young ones. You also need to give the Commander 200,000G.

Character editor

In it, without "Chaos Mode" and other functions in the settings, you can create any prisoner by setting the following parameters:

• Age (2 options)
  
• Height (20 options)
  
• Fringe (25 options)
  
• Hairstyle (14 options)
  
• Hair length (30 options)
  
• Hair color (75 options)
  
• Hair lightness/brightness (150 options)
  
• Eye shape (60 options)
  
• Pupil size (30 options)
  
• Eye color (99 options)
  
• Eyebrow size and placement (20 options)
  
• Special features (20 options)
  
• Breast size (99 options)
  
• Body width (99 options)
  
• Skin color (99 options)
  
• Pubic hair (10 options)
  
• Pregnancy (11 options)
  
• Character (7 options)

How to get into the "Secret Club"

To do this, you need to get the item "Dodgy Invitation". You can get this item by patrolling the "Noble District", from a random "suspicious man" (See image below).