In Another World with My Smartphone, Vol. 6 (Manga)

＂Touya and the rest of the team make their way to Eashen to find some mysterious ancient ruins...but get caught up in an Edo period-style battle to save Yae’s father and brother! While Touya impresses onlookers with more unique magic and creative uses of his smartphone, the group is guided toward their true reason for visiting Eashen. What new challenges await them at the ruins? The summoning of the Black Monarch, an underwater temple...and the sky garden Babylon!?＂--