It's a road roller.

and poor Kaito just gets run over for no reason.

Zebrin said:
and poor Kaito just gets run over for no reason.

It's not "for no reason" -- Len's dragging the poor sap down with him.

Also, it's firmly established that Kaito is the Butt Monkey among the Vocaloids. Not even Spell-My-Name-With-An-S Gakupo can unseat him.

The road roller is from a song done sung by Rin.

hahahaha... dang... love how len say "Were those... breasts, just now?".... and also poor kaito..