Summoning To Another World

A teenage schoolboy named Cini, who was walking home, found a mysterious circle in a small street. Out of curiosity, he approached the circle and realised it was a magic circle. Not until there, when the circle swallowed and threw himself into a very dark room. He was surprised to find two of his friends who were in the same place. This is the story of those who are summoned to another world! Will they help or run away? And what happens after they win the war? Will the problem just end?