At 100 discipline points, provided you have at least 200 affection, take them all to the river, will unlock the next tier and allow nakedness at the beach
At 1000 discipline points, provided you have unlocked sex with them all, next morning you can talk and reveal the proto-harem and unlock the next tier
At 2000 discipline points, provided you have a bed, 400 at least with each and 200 for them between each other you'll get an event at night unlocking the harem.
At 100000 discipline points, at nightfall you will unlock an unleashed harem, max libido is 999, heroines gain libido very quickly.
For Akemi: have three battles with wolves, last battle must be alone with her.
For Yumeno: No idea, does happen randomly eventually, always happens.
Bring up affection until you can touch her breats, fondle them 40 times, on the next sunny day take her to the beach at the very start of the day.
And a few tips:
Dirty talk increases displine disorder by 4
Naked volleyball at the beach increases displine disorder by 20, affection towards protag by 10, between heroines by 10
Wine increases protag affection by 4, between heroines by 5
Ruins (NW) have books needed to craft specific items (medicine and specials)
Beach (S) has water tanks, tarps, volleyball, cooking pot, wine
Leaf bikinies: large leaves are gathered from herbs gathering, make them wear the bikini in the status menu