まるです。

まるさん、食べてすぐ寝ると牛になりますよ。
Hey Maru! When you eat and sleep immediately, you become the cow.

「別にいいですよ」
Maru:[ I’m ok! ]

「おやすみなさーい」
Maru:[ Good night……]
In Japan, there is a legend of becoming a cow if sleeping at once eating.