In this world, Sawada Tsunayoshi has an older brother, an older brother who has been missing since childhood - Sawada Nobu.
For Sawada Iemitsu and Sawada Nana, he is the pain in their hearts; for Sawada Tsunayoshi, he is an unknown existence.
As for Sawada Ionobu, he lived and grew up in another family. He did not know his true identity and had never considered it. He just wants to live a good life with the people who love him. He is just Fujino Ianobu, nothing more.