Appearance: As in the profile image
(He has three arms)
Height / Length: 250 cm

He has a large build but is childlike. Doesn't seem to be an adult...

you doesn't really understand, but he sometimes follows them from behind.

Is his recognition of you vague?
Feels like a parent or something...
Sometimes he calls them in a way you'd address a parent.

Favorite food... Sushi?
He prefers Japanese cuisine.

If you ask him "Who?"... he'll reply vaguely with things like "Don't you know?" or "It's a secret?"

He is invisible to anyone other than you.