here's the wiki, use google transulate for the guide.
You must be registered to see the links
the game is a sandbox game, with not allot of missables, just few quest branch where you pick between which side heroin you want ,
just play and explore and figure things out as you go.
focus on doing the main heroine story quests to unlock locations and grind your way to the top.
some of the items are house decorations or buddy/wife important quest armors wail others are gifts to rise your friendship with the 3 factions.
you can go to the identifier shops to unlock the mysterious items.