Yuuki Yuuna ha Yuusha de Aru: Hanayui no Kirameki vol.1

During club activities, the six members of the Sanshuu Middle School Hero Club are consumed by a mysterious light and wake to find the world forestized and invaded by Vertexes. Their Transformation App — which should have been retired — has returned. After repelling the first attack, a girl named Uesato Hinata appears and explains the situation: they are inside the Shinju, a union of land gods on the verge of internal collapse. The rebelling gods are creating the Vertexes. Heroes from across all eras have been summoned to suppress the rebellion before the Shinju loses its power entirely.