Monster Strike: Mera×Death - Shinigami to Boku no Ijou na Koi

Sinopsis

Six years ago, a massive explosion occurred in the town of Ouma, but miraculously, there were no fatalities. In this city where a mysterious sphere called "Glass Sun" floats in the sky, a boy named Mera Kagari, who feels out of place and lives a boring life, meets a mysterious girl named Thirteen on his 16th birthday. Her encounter with her brings vibrant colors to Mera's previously monochrome life, but at the same time, strange occurrences begin to unfold in the city. (Source: MAL news)