Tajimamori's first appearance is when Rin sees him after she is killed by bandits in Japan 1000 years before. But because of a Time Fruit that entered her, she revives and she falls in love with him. But for most of the series, however, he limits his contact with Rin to telephone calls for several years.
He appears again in the final episode (Episode Six) when Rin is in Apos' castle, and he helps Mimi and Mishio to find her. After explaining that Apos wants to become the new eternal Guardian by sacrificing Rin to Yggdrasil, Tajimamori opens a portal to Apos' castle for them.
Upon seeing Rin at Yggdrasil again, the two make love until Apos arrives, kills Tajimamori, and pushes Rin into the tree. In Apos' defeat, Rin feeds him Tajimamori's and Laura's Time Fruit while he is consumed by the tree. In the epilogue, Rin gives birth to Tajimamori's son and continues living in Apos' castle with Mimi and Mishio.
It turns out that Apos is Tajimamori's 'son'. The Maenos (Kouki, Teruki, and Mishio) are also all Tajimamori's descendants. Rin also reveals in the credits that her and Tajimamori's child was born a normal human boy but with the added exception of having a natural link to Yggdrasil. This link will continue to spread throughout the species with his descendants implying the day will come when humans will finally be able to understand, accept and learn to live in harmony with it.