Isekai Kaeri no Moto Yuusha desu ga, Death Game ni Makikomaremashita

Isekaito is on a school trip with his classmates, enjoying his daily life as a normal high school student, when he is suddenly caught up in a death game controlled by a man in military uniform. The weak will die and the strong will survive... but what the man doesn't realize is that there is a powerful former Hero from another world amongst them.

(Source: Comic Days, translated)