MINAMOTO no Yoshimitsu or "Shinra-Saburo" traveled east to support his older brother MINAMOTO no Yoshie in Gosannen no Eki (the Later Three Years' War) in 1087, but Tokiaki chased after and asked to accompany him to the battle on Mt. Ashigara in Sagami Province.
寛治元年（1087年）、新羅三郎こと源義光は、後三年の役を戦う兄源義家を救援すべくため東上するが、時秋はこの後を追い、相模国足柄山にて戦場への同行を申し出る。