[quote=@Rin]
I figured he was named after Osamu Tezuka. ^^;
[/quote]

He isn't.

[quote=@Savo]
<Snipped quote by Letter Bee>

Oh, so you're saying Osamu is dead, that's nice to know.
[/quote]

More like he's named after the dead Osamu by said dead Osamu's ex-lover, who ended up marrying Ruki/Rika.