What's the best use of the "Retard in Lecherville" trope you've seen in japanese media

[TheGhostPizza1234]

For me it's the Jrpg President Yukino and an ecchi/borderline hentai manga called Tennen Kajuu Sayaka, the latter never actually gets raped because of deus ex machina, but after the main series was the mangaka went all out in the prequel and made her get fellatioed and cunnilinged without knowing and also later bukkaked, unfortunaly it was also cancelled in 2009 and ended on a cliffhanger on whether or not she was actually tricked into sex, too bad, i guess it was too good for it's era