In 1582, Tadamasa started to work under Nobunaga ODA as a page but was dismissed and sent back to his mother by Nobunaga; Nobunaga thought, upon finding Tadamasa in a fight with one of his colleagues, that he was too young to do the job.
天正10年（1582年）、織田信長に小姓として出仕するが、同僚との喧嘩を信長に見咎められ、まだ幼すぎるとして母親のもとに返された。