What kind of dog is this?

to me it looks like a german shepherd puppy

It's a ロットワイラー, 恋人 puppy.

if あなた had showed e the tail i would have もっと見る information but to my guess its a Tibetan マスチフ, マスティフ または another Tibetan dog mixed dog look it up for the 子犬 looks. This pup looks very similar, ask for もっと見る info

Well, it looks like it will grow up to be quite a big dog...