Dolly Kill Kill

Iruma Ikaruga is living his best high-school life … until mascot-looking aliens from another world invade with their flesh-eating bugs, seemingly hell-bent on destroying humanity violently and effectively! On that fateful day, Iruma loses everything … his normal life, his best friend, and his crush … until six months later, when he catches a glimpse of her again. Is all hope for humanity—or just Iruma himself—truly lost?
(Source: Kodansha USA)
Chapter count includes two side stories.