For Miyuki: Get to 20 Affection w/ Homework at 100. Then sleep with her ONCE. You should get a scene where she sucks her husband off, but he falls asleep. Then your character should do the kitchen scene automatically around noonish. And for the last part do NOT sleep with Miyuki. She should start masturbating thinking about you while alone on her bed.
For Yui and Rio you just need to get your homeworks at 100 then there should be an auto scene.
BONUS: If you want to get a blowjob from Miyuki, be sure to let your Lust gauge reach 100 at least once. Then once you finish the 40 affection event, talk to Miyuki at night, choose to sleep with, then she should take you the bathroom for a BJ.
EDIT:If you want to see an actual walkthrough, just check out the steam site:
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