Toshito Kutajima starts as an ordinary classmate of Tomo Harada, but romantic feelings for her begin to grow. As Tomo experiences unexplained disappearances linked to her search for her missing father, Toshito becomes increasingly concerned and watchful. He witnesses one such vanishing and ultimately uncovers her secret ability to travel through time.

Motivated by his feelings and worry for her safety, Toshito actively pursues Tomo on her next journey through time. He successfully follows her back to Japan's Edo period.

Stranded together in the past, Toshito becomes Tomo's steadfast companion and protector during her perilous search. He shares the dangers she faces, observing the historical setting firsthand, including hostile encounters with suspicious locals and authorities. His presence offers Tomo vital emotional support and practical aid; he actively assists her investigation, helping navigate the unfamiliar world and avoid capture.

During a critical confrontation with era figures who view the time travelers as threats, chaos separates Toshito and Tomo. While Tomo escapes back to her own time, Toshito is left behind in the Edo period, permanently stranded. This marks the conclusion of his known journey.