After Nobunaga died due to Honnoji Incident in June 1582, Kagetomo obstructed the advance of the Mitsuhide AKECHI force toward Omi Province with his older brother.
天正10年（1582年）6月、本能寺の変で信長が死去すると、兄と共に明智光秀軍の近江国進撃を妨害した。