well i can't tell you what to do but i'll tell you what i would do! the creator has said all characters are 18+ but i personally believe she said that to save her own ass so no one can criticize her multiple characters who very clearly look underage. i'm not comfortable with nsfw media that has characters who look like they are designed to look underage.

you could argue it would be okay to buy figures of the characters who look like adults secondhand. i personally would not do this, because it would bother me if people looked at my collection/mfc account and assumed i support nekopara and therefor the questionable thing i discussed above. i would feel the need to hide the fact that i would own nekopara figures, and then i would feel guilt that i do own them but won't dare to openly support it.

that's the way i am. there's also a discussion to be had about caring what other people think, but i'm only intending to imagine what my experience owning nekopara figures would be. i know there are many many many people who don't gaf at all what people might think about them and their collection, so maybe your experience would be completely different!