In 1632, Yasutsune visited Nagayoshi IKEDA with his older brother Yasunobu IKEDA to complain about Nagayoshi's will (stating that his first son, Nagatsune IKEDA, and the second son, Nagazumi IKEDA [the son-in-law of his older brother Yasunobu WAKIZAKA], would respectively inherit the two halves of Nagayoshi's territory), but there, Yasutsune had a fight with Nagayori IKEDA, a younger brother of Nagayoshi, and was killed by him.
しかし寛永9年（1632年）、池田長幸の遺言（長男・池田長常と次男・池田長純（兄・脇坂安信の娘婿）とで領地を半分ずつ相続する）に不満を持った兄・安信と共に長幸の下に抗議に訪れたが、長幸の弟・池田長頼と口論になった末に殺害された。