I wanted to make a post that contains my ideas for how the relationship system with work in the next umichan game. Feel free to leave feedback on these ideas.

there will be 3 main statuses. possibly 4 indicated by icons.

for the purpose of this description we will assume the playable character is Maiko.

also just for this example we will assume the timer frame is set in UMCH/CC
I will use David, Luma, and Lynn as examples.

Normal – characters will act as they normally do toward the player character based on their own personalities.
for example, David will be kind of a dick, Luma will tease you, and Lynn will be nice as usual however Cain will block most interactions.
some sexual interactions for certain characters are available at this level but most are not.
Each character has a specific requirement (or multiple) that will enable a increased relationship status to friend.
I am also thinking about having a Hate status. Not sure if I will use the word “Hate” but you get the idea.

Friend – characters will view the player character as more friendly terms but still have their personality.
David will lighten up on his vulgarity, Luma will point out she is joking, Cain will lighten up a bit.
most character sexual interactions begin at this level.
it is possible to fall back to normal status based on actions or acquired friends.
outside of passwords I don’t plan to have it where the player can be friends with everyone at the same time.
characters may drop a tier down if you bring them to sexual stuff they are not interested in.
character can meet you in certain locations.

Best Friend – characters will view the player character with admiration (in their own way).
requirements for dropping down to the previous tier is less common.
more character sexual interactions at this level.

Hate? – character is be harsh/distant from the player character. It is a bit more difficult to get out of this tier once in it.

___________________________

a few examples of the aforementioned requirements.
+this requirement will improve the relationship tier with this character to the next tier up.
++this requirement will improve the relationship tier with this character by 2.
if multiple are their either or is needed. you don’t need both.
–this requirement will reduce the relationship tier with this character to the next tier down.
– –this requirement will reduce the relationship tier with this character by 2.

also I should note that some of the player character status will be things such as:
most recent (person you had sex with)
recent activity (study, sex, sport, working, etc)
current friends/enemies with
recent photo uploaded

David (not final example)
Hate:
++Friend with Joiry
+recent activity was detention
+Defeat Jeni in a sport
+recent upload sexy photo

Normal:(hentai needed to move up from this tier + will activate hentai options)
-lose in any sport activity
-recent upload studying photo
-David sees player with nerd character
+Over 80% trouble
+talk to David in any revealing clothing

Friend:(David can travel with player character, more hentai unlocks, certain characters are repelled)
-successful in academic activity
-David sees player with nerd character
-maintain low level of trouble across multiple tasks
– -upload sexy pic with another male
– -travel with another male and see David
+get in max trouble and caught while traveling with David
+Talk to David while traveling with Joiry

Best:
-Be seen by Holly or Jeni while traveling with David

as you can see a lot of things can move the tier up or down, but when you get into best there are only a few things that will cause it to decrease.

Not all characters will have specific requirements like this. some characters will all generally have the same requirements base on their character type. like non specific nerd type male characters maybe have a lot of shared requirements. with possibly only 1 or 2 specific differences.