Takeshi Yamashiro is a 26-year-old businessman working at Shitamatsu Electronics, a graduate of K University. His primary hobby is caring for dogs, especially his Bernese Mountain Dog, Josephine, whom he rescued as a puppy and raised.

He frequents the cafe Hakobune, regularly ordering strawberry cake. There, he develops an interest in the waitress Arashi, stemming from her resemblance to a girl who saved him from drowning approximately ten years prior during a nighttime swim. He remains unaware that Arashi herself was that rescuer through time travel. His polite demeanor and affluent background fuel Hajime Yasaka's persistent jealousy, viewing Takeshi as a romantic rival due to his rapport with Arashi.

Takeshi experienced a rebellious phase during his teenage years, which ended after an encounter with Yayoi Fushimi through time travel, leading to significant personal reform. His reserved nature and strict upbringing cause discomfort around assertive romantic advances, particularly those from Sayaka, the cafe owner.

Notably, attempts were made to pair Takeshi with Yayoi for time travel purposes, as her ghostly form required a connection to a living being for energy sustenance. Contrary to expectations, Yayoi formed this connection not with Takeshi but with his dog Josephine.