is the girl in the right in the main image a gloomy type of girl like Tomoko from Watamote? if so, my interest has been catched,
She has the look, and a kind of melancholy voice, but she's mostly an optimist, from what I remember. Although, for the Halloween update there was Samara, who sort of has a Tomoko look, although she's a literal "Ring-styled" zombie girl.
even though i'm not the biggest fan of jigsaws.
There are various difficulties, which become progressively harder, due to added mechanics at the higher modes. If you play on Easy, all the puzzles can be completed in probably 5 minutes or less, even if your not super great at jigsaws, and if you manage to put a pieces in the right spot quickly, you perform a combo, which causes the game to assemble some stuff for you. So, if you do a high enough combo, the game might even finish the whole puzzle for you on that mode.
I haven't played since the Halloween release, so there might me a gallery to view unlocked stuff now, but if not, you might have to replay both puzzles for the girl, to get to the sexy stuff, although you might unlock new CG's while doing that. It's not a bad game, plus doing jigsaws can be kind of relaxing and theraputic... especially if things get sexy afterwards.