I'm not one to make guides but this game is indeed tricky without one, so there you go.
You have four meters to worry about:
Fatigue (lower is better)
Vitality (if it hits zero, you die)
Quota (This is only important until Chapter 5)
You have two goals: (1) get money and (2) fuck girls. You need money to buy food from the convenience store so you don't starve (if you're too broke you can still eat out of the trash can by the restaurant though, but of course it's not recommended).
1) How to make money:
1- Work at the restaurant (only between 10:00 AM to 05:00 PM)
2- Play music at the garbage dump for the local animals
3- Film people having sex (yourself included), and sell it to the loaded salaryman between 10:00 PM to 04:00 AM.
2) How to make out with the heroines:
You can have sex with Lilim whenever you want, but if your vitality hits zero you die instantly
Lilim has three different stats--Naughtiness, Service, and pervertedness.
Different sex moves level up different stats, which in turn unlock more moves from the same category.
Lilim also has a status that is shown when you enter the sex menu. As far as I know, it is just for flavour.
Sub-heroines: Every lady has an affection level that starts at zero and goes to 100. Like in all of DoujinOtome's games, there are "soft caps" at 20, 40, 60, and 80, where you'll need to trigger an event to be able to raise affection further. You can raise affection by giving a random item (1 point), a gacha figure (3 points), or a Pretty Cristal (5 points).
Satou (Brown-haired normal looking girl who works at the convenience store):
She leaves her house around 7:00 AM to go to the convenience store every day, and she comes back exactly at 7 PM.
(0-20 Affection) Just talk to her and give her gifts
(20-40 Affection) Same as above, at 40 or so she'll talk about earthquakes when you go back to your room one will happen, where it opens a small hole between her apartment and yours, go back and talk to her about it.
(40-60 Affection) You'll feel a "presence" watching you at night, when this happens have sex with Lilim, after that talk with her about it.
(60-80 Affection) Same as above, but this time she proposes an interesting solution.
(80-100 Affection) Just talk to her and give her gifts
Nanjo (Blue-haired MILF who lives in 101):
She sells charm and courage enhancing items that are generally worthless because they're expensive and you can raise your stats pretty easily. She's lonely and wants to cheat on her husband with someone else (wink wink).
(0-20 Affection) 7 AM, just watch her husband and her talking.
(20-40 Affection) Same as above
(40-60 Affection) An H-scene happens around midday, to trigger just watch it from her window.
(60-80 Affection) She'll talk with you about her suspicion that her husband is cheating her with someone, to find it who it is, walk close to the restaurant around 03:00 AM or so.
(80-100 Affection) Another H-scene happens around midday, to trigger just watch it from her window.
(100 Affection) 7 AM, just watch her husband and her talking.
Kagami (Red-haired fitness fanatic who works at the gym)
A gym rat who can't afford a whole shirt. You can catch her running around 10:00 PM or else around 05:00 - 06:00 AM. She is the one who invites you to the gym.
(0-20 Affection) Just talk to her
(20-40 Affection) Just talk to her
(40-60 Affection) Talk to her, her gym wants to expand their business and proposes home service training sessions, after knowing of the news, just call her at your apartment.
(60-80 Affection) Talk to her, request a "Massage".
(80-100 Affection) Talk to her, request "Naughty things".
Yoshikawa (Blonde teacher who lives in 203)
Talk with her around 04:00 PM when she is coming back home after work
At midday, talk with one of her students who is close to the area
At 05:00 PM, talk with the same student but this time when he's leaving her apartment.
At 06:00 PM when you see heart marks leaving from her apartment, take a peek over her window. After this you'll acquire the "Anal" sexual position.
Side Characters (or Places):
Peerless Master (He looks like Master Roshi from Dragon Ball)
You can find him in a desert alley close to the apartment complex where you live from 08:00 AM to around midday or so. He sells you special sex skills.
Kazuki-kun (A boy who's obsessed with Fidget Spinners)
You find him close to the restaurant from Midday until sunset. If you win all challenges he throws at you, you get a special sex skill.
The four animals who gather around you when playing the guitar on the streets. If they're pleased over your performance and you talk with all of them they give you a new sex position.
Radio Exercise Man
A middle-aged guy who's a little depressed because people do not gather around in the morning and do radio exercises anymore, he still does it because he wants to maintain and improve his body's health, if you invite a sufficient number of people to join him on his morning routine, when you exercise with him you get special bonuses over the day.
If you work 5 times at the restaurant you gain the capability of zooming-in on sex scenes.
A gacha figurine fanatic, if you get him all 10 figurine variants available on the local gacha machine, he gives you a special prize.
He appears around 03:00 AM at the same place as the Peerless Master, he sells every sex position in the game, you can get it for free just playing, but it's there if you want a shortcut.
Chapter 5: Getting the necessary Info (where are the 5 clues)
1- Middle-aged man close to the apartment complex you live.
2- A Young man close to the restaurant
3- A middle-aged woman close to the convenience store
4- Working part-time at the restaurant
5- Reading "Understanding Succubi", sold at the convenience store.