@Pinka According to some source called Pixiv and a game 774 made (don't understand this one), His name is Hachiouji and/or Naoto. (As in I am not sure if it is Hachiouji Naoto or if it is simply a different depending on sources). Could be different again as these sources are not actually part of the manga.
On an unrelated note, Nagotoro's three friends are "Gamo-chan" "Yoshi" (may be a nickname) and Sakura (not a nickname).
So the only two confirmed names in this story is Nagatoro and Sakura.