Snowball Earth, Vol. 3 (manga)

After meeting the survivors of the icy apocalypse who are holed up in Mishima Mall, Tetsuo makes a few attempts at making friends. His defeat of the kaiju that attacked the mall has made him a hero to the inhabitants, but before he can establish any firm relationships, a new threat appears. Another band of human survivors, led by the mysterious Colonel, wants to seize control of the mall - and they have their own kaiju to do it with!