Kiroumaru

The supreme commander of the Giant Hornets colony. Despite having orders to kill the children, he risked his life to help them escape.

Much later on, his colony was destroyed by a Fiend sent by Yakomaru and he barely survived. He was briefly held captive at the Temple of Purification before Saki released him. After that, he assisted Saki and her group to Tokyo and eventually sacrificed his life to defeat the Fiend.
(Source: Wikipedia)