Tenchi Muyo! War on Geminar

Isekai no Seikishi Monogatari

The story is set in an alternate world called Geminar, where countries have fought endless wars with replicas of humanoid Seikishi weapons that they found in ancient ruins. 15-year-old Masaki Kenshi, the half-brother ofTenchi Muyou! protagonist Masaki Tenchi, is summoned from another world to Geminar.