Although Yoshimoto accepted the submission of Hirotada MATSUDAIRA in Mikawa Province, who felt threatened by Nobuhide ODA of Owari Province, in exchange for Hirotada's legitimate son as a hostage Takechiyo (later Ieyasu TOKUGAWA), a kokujin ryoshu (local samurai lord) of Tawara-jo Castle in Mikawa Province (Tahara City, Aichi Prefecture) named Yasumitsu TODA, who was in charge of escorting the hostage, betrayed Yoshimoto and sent Takechiyo to the Oda clan, Yoshimoto's enemy.
三河においても尾張の織田信秀の進出により圧迫を受けた西三河の松平広忠の帰順を受け、広忠の嫡男・竹千代（のちの徳川家康）を人質に迎え入れようとするが、護送を請け負った三河・田原城(三河国)（愛知県田原市）の国人領主・戸田康光が裏切って護送中の竹千代を敵方の織田氏に送り届けてしまった。