A menace of huge monster-like insects is plaguing the land of Edo. Too powerful to be subdued by ordinary folks, the creatures are hunted by the Insect Magistrates—a group of warriors who specialize in various secret arts and combat styles. To bolster their strength, they summon Genjuurou Tsukishima, the master swordsman from the Tsugaru Province.

Due to an unfortunate incident, however, Genjuurou is incapable of answering the call and sends his son, Jinbee, to serve in his stead. Determined to atone for the incident caused by his own cowardice, Jinbee agrees to travel to Edo and join the Insect Magistrates. Armed with his fiery spirit and unwavering resolve, Jinbee vows to become a stronger samurai and rid Edo of the insect threat once and for all.