I know what Yuumi needs to do. She needs to fuck(forcibly if need be) Koichi, but use her own condom that she poked holes into so she gets pregnant. That way, either one of two things will happen.
1. Koichi will straighten up and date her properly.
2. Koichi will be an asshole and we will have nice boat ending.
Anyways, this show was over at episode 20 but I am just watching right hoping for Nice Boat ending.