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.

OVAs bundled with the 15-17th volumes of the Mushibugyou manga.

The entire countryside comes to a halt midday to witness a rare solar eclipse that is rumored to allow the average person to see Mushi. Unable to avert their gaze, the air is full of awe and wonder—but those who know the Mushi are preparing for the eclipse's aftermath. Based on a prediction from Tanyuu Karibusa, the cursed recorder, Mushishi Ginko finds himself in a very unlucky farming village. Immediately following the solar eclipse, a strange black cloud begins to gather in the sky and blocks the sun once more. Suspecting it to be the work of a Mushi known as Hihami, Ginko seeks to liberate the village from perpetual darkness. However, it seems that not all of the villagers are eager to return to the light.