Anime column writer Maeda Hisashi criticized the episode 1 of Ore no Imouto ga Konnani Kawaii Wake ga Nai
that the characters under 18 were described to have purchased adult games. Popular adult game producers such as Overflow, feng, UNiSONSHIFT were credited as cooperators for permitting the use the package images of their games. Maeda apprehends that the anime would provide the police and the anti-adult game public with a good excuse for imposing tighter regulations.
In Japan, a local ordinance prohibits minors under 18 from buying adult games.
Source: Maeda's tweet
, Togetter about this issue