Sakai Masanao committed suicide on the battlefield. There is another print in this series of Masanao's son, Sakai Kyuzo, who also died on the same battlefield.
Masanao was a loyal supporter of Oda Nobunaga. When the latter was confronted by Asai Nagamasa (1545-73) and Asakura Yoshikage (1533-73) at the foot Mt. Hiei, he sent Masanao behind the enemy lines to capture the enemies food supplies. He succeeded to some extent by frightening away the soldiers who were guarding these. Masanao loaded the food onto a ship to take back to Nobunaga. While he was waiting for a second ship to take him and his men back too, the enemy counterattacked.
Here, in this print, Masanao is standing on a large tree trunk looking for the ship which would take him back to his master. Clearly it didn't come in time.