Minase, Akiharu

水無瀬明春

The Professor teaches folklore at a university. He holds a unique perspective on the subject and wrote his dissertation on it. Multiple academic societies have treated his papers as heresy. He is extremely curious about other worlds and monsters.
In 2020, he is in his 60s.

Spoiler

In 1970, 50 years in the past (thousands of years in alternate world time), Akiharu and his sister Miyuki Minase were part of a mass disappearance of children. The children had been pulled into the other word by Master. Most of the children died, but Akiharu and his sister survived thanks to becoming partners with Kemonogami. Akiharu became partner to Gabumon while Miyuki became partners to Renamon. Gabumon wasn't very strong though, which lead to Akiharu protecting him instead of the other way round. The group are eventually cornered by Kenzoku and Miyuki sings the song of the Minase Maiden, creating a portal back to earth. Before they can enter, the Kenzoku attack and Haru finds himself frozen in fear. Feeling pathetic about how weak he was, Gabumon's desire to protect Akiharu causes him to evolve to Garurumon. Before he can protect him from the Kenzoku, though, the portal sucks Haru inside, forcing him to abandon his sister and their partners. Believing Haru left willingly, Garurumon feels deeply betrayed, believing that their bond was just a lie the entire time, which causes him to hate humans and start sacrificing them over the course of thousands of years (50 years in human world time).
Akiharu then wakes up in the human world and is found by a group of farmers, who he asks for help. He tells them about Miyuki being taken by fog monsters, though they didn't believe him and instead search for her nearby, leaving Akiharu upset that no one believed him. Due to no one believing him, as well as his traumatic experience, Haru ends up suppressing most of his memories about the other world.
Akiharu then spends 50 years separated form his sister and Garurumon (thousands of years in alternate world time), and dedicates his life to studying the Kemonogami. He becomes a Professor, teaches folklore at a university, and becomes a published author — writing a book named The Kemonogami Legend.
He eventually ends up being transported to the alternate world once again, and comes across Takuma Momozuka and his friends, becoming part of the group trying to return home. Miyuki and Haru were part of the group, with Akiharu confused since they looked exactly like he and his sister did when they were younger.
He eventually remembers his real name, though even after the children learn it — they still refer to him as Professor.