Higher H Compatibility will unlock more positions as well as make the the partners become more comfortable with positions that don't match their preferences. Compatibility also reduces the time expended for each position taken; at minimum compatibility 4-5 positions can take up a full period, at maximum compatibility the time cost for each position becomes negligible. Characters with the Easygoing and the Lewd / Perverted traits will increase compatibility faster. Both partners will show a satisfied or dissatisfied face during a position, depending on whether they like it or not.
At "Great" or "Perfect" H compatibility a pair will like even positions that don't match their preferences, although it still won't increase the compatibility faster.
H Compatibility increases slowly with every H and will increase faster by choosing positions which match sexual preferences.
Blue Hearts indicate a position that satisfies one or more of the player's preferences, and increases compatibility slowly.AA Heart Blue.jpg
Pink Hearts indicate a position that satisfies one or more of the partner's preferences, and increases compatibility faster.AA Heart Red.jpg
Pink and Blue hearts match both partners' preferences, and increases H-compatibility quickest.
The number of hearts seen is proportional to the increase of H compatibility.
Orgasm positions multiply the effect for the partner who orgasms.
Positions that match multiple preferences can only be identified through H dialogue but their effect is added to compatibility increases.
Compatibility only increases the first time a preferred position is selected during an H session.
Though H-compatibility doesn't directly affect Love, Love increases when a partner's preferences are satisfied. The Ahegao state doesn't grant any additional increases, but does increase Love.
H Compatibility between two characters will sharply decay unless they are lovers and keeping it up with more than 2 sex-friends is almost impossible.