Resolved MC goes back in time, post apocalypse, lots of insect type monsters

He goes back in time, when he awakens, he finds himself in his school. like 20 something minutes before apocalypse (some kind of wave). He tells everyone about how the apocalypse happens 20 something minutes, no one believes him, the apocalypse happens, electricity and mobile network goes down. then creatures attack school. he tells others what happens to them during the apocalypse. theres this married teacher character he likes who has healing powers(probably saved him last life). He hates this sword saint girl classmate. MC uses this frozen blade

 

Apocalype summoner

 

Thank you