Honestly I much prefer that Hotaru stays with Naoto, for the most that he's not the best role model, he's still better than those old farts that just want to force their way (if you know what I mean) with Hotaru and hurt her just because she can heal back to normal.
Even if he's the "anti-hero" here like Venom or Deadpool, Naoto still wants the girls he fucks to feel good, specially Hotaru.