Kamihime Project does have guilds, but you don't really need one. They do help during events (so you can send request help to your other members), and I believe you do get additional rewards if your guild ranks high during them, but you can make do without one. The events themselves last for around seven days, and you don't need to log in during specific times to do them. There are such things as "Burst Sessions", where you have a stretch of time (twice a day) where during raids your Burst Bar is automatically filled at the start (the guild leader sets the time, IIRC). It's great for grinding points/drops/etc., but again is more of a bonus feature than anything else.

In-regard to Sengoku Providence, I'll probably be leaving it myself after I hit 100k points. I've put in the time so far I kind of want to finish it up, but I won't be going for the next one. I'll likely log in daily for the free items in the hopes that they change things, but if not I'll just drop it entirely and focus purely on FKG and KP. I'm thinking maybe a month of just logging in, and if things are the same then, I'll probably just remove it from my daily routine entirely.