A bit of trivia: I may be the only one who actually looks at the background CG images, but #157 is an exact copy of the Genshiken clubroom as depicted in the Season 1 anime OP, down to the placement of the TV set, the gaming consoles, and the items on the table. The only things missing are the anime posters on the windows.

If anyone wants to check out the OP for reference, here's a link:

http://www.youtube.com/watch?v=_CgcgckUflQ

The image appears at the very beginning, so you don't have to wait for the full video to load.

Base +7, Panuru +29, karorogunso +8, draconian196 +10, yakuzaoutcast +11, Isaac Lisianthus +8, Zero Angel +36, Ark_Thompson +7, danixxx +31, LionMaru +9, Herp in your Derp +19, hakkibulut69 +16

Most of the background CGs are also free (I believe) content that several amateur doujin game devs use: if you play a bunch of them you'll recognise a lot of the backgrounds.

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[はやぶさスター] 蒼い子つかまえた (スマイルプリキュア!)
[Hayabusa Star] Aoi Ko Tsukamaeta (Smile PreCure!)

ID (DLsite): RJ098841, RE098841

Base +12