 If you liked
FLCL
|
 ...then you might like
Sweat Punch
|
(As Sweat Punch is collection of stories indipendent on themselves, this recommendation concerns only Garakuta no Machi part)
In both, a young boy encounters robot that decides to hang around him. Both anime have robot that gets bigger by eating metal scrap and other metal stuff. FLCL is more dementia.