Isekai Nidome no Ossan, Dou Kangaete mo Koukousei Yuusha Yori Tsuyoi

Takayanagi Riku is a 32-year-old office worker with no particular characteristics. He actually has a special past in that he once saved another world as a hero, and now he lives in Japan as an ordinary office worker. But one day, he gets caught up in a group of three high school students and is summoned to another world again!? Riku is confused by this sudden turn of events, but he encourages the high school heroes, who are even more confused than he is, and decides to teach them how to survive in another world...