Nagumo has a laid-back attitude and usually a constant smile. He is known to be very annoying, to the point people around him want him dead.
Nagumo is easygoing and carefree even in the most inappropriate situations. Despite his cheerful behavior, he can also be deadly serious when the situation needs, especially with things important for him. When he isn't in is on mode, he is more introverted and quiet, even lazy. He can be very loyal to people he is fond of.