Indeed! This is a good use of the artbooks.
It doesn't include like an R18(genitalia'd/nippled) version of the arts existing in-game, but any other illustration not included in the game had them, as well as little notes.

Then a particular cameo art has just their names on it w/o explanation, like "it's them. You already know much about them, 'nuff said." xD
Though it's kinda counter-point to how the Touhou series' character description goes, since they're differently described in every appearance.

I wish it had moar~. I feel it could have more flavor text & stuff should Pico Games wishes to expand more on it. But all in all a nice artbook still~.

(edit) Pico Games also mentioned they'll add Grim Reaper in the artbook at a later date~. They output alot more arts that could be related to YSS characters in their X(Twitter), so be sure to check them out over there!
https://x.com/PicoGames_off/status/1860136075987157240

Originally posted by ruff1298:

the game itself doesn't have genitalia or nipples but the art book certainly does

Are there any mods that fix this situation?