WAIT. I actually have an alternate idea on how to handle the Kan thing;
If you've reached a high enough relationship score with Yuna, Kan would stop entering her room to check up on her. Instead, he'll go and knock the doors, which would obviously increase her wakefulness meter.
The player can counteract this by buying upgrades, such as buying a headphone which you can give to her at the start of each night. This will muffle the sound, reducing her wakefulness meter when Kan knocks on the door AND when her phone randomly rings in the middle of the night. You can also use the hand option and block her ears yourself, but you'd have to stop all of your previous actions unless you have the Master Hand upgrade equipped. Third upgrade would be sound-proof walls, which automatically reduces the wakefulness meter gained from Kan knocking the door permanently.