Futatsu no Gespenster(2020)

Futatsu no Gespenster

The Gespenster are monsters that appeared in the country of Lang-Yuba as a result of experiments on twins during the war. Alan, an orphan who was himself a test subject, is on the run in the city to avenge his brother who had become a monster...

(Source: Shounen Hana to Yume, translated)