I know this is late in the day, but being a nerd I feel my duty to reply
FM Towns sure has hentai....lots of it.
But really for gamers it is more about its library of arcade ports, the SEGA games on it were actually ported by CRI (owned by ex sega holding company CSK), and it also has uber versions of Muscle Bomber (Capcom), Splatterhouse (Namco ported by Ving), and Neo Geo ports of Samurai Shoddown & Viewpoint.....among lots of others.
Out of interest, does anyone know if the FM Town version of SOTB has the same AST as the PC Engine one??