Masahiko Ogai(奥涯 雅彦 Ōgai Masahiko) is a former professor who disappeared after an incident at the university hospital.
Due to his curiosity about possible hidden knowledge, both supernatural and occult, Ogai amasses an enviable collection of fantastical scriptures and stories.
Ogai is responsible for Saya's arrival in the world after he summons her; this is due to his gullible and willing nature making him the perfect catalyst for a test designed by Saya's race to find intelligent life to imitate, invade, and convert; a la von Neumann probes.
Finding himself immensely intrigued by alien life, no matter how perverse, Ogai sets about running tests on Saya; he gives her the name Saya after a childhood cat that he may also have performed experiments on, leading to some speculation about his unusual morality as a surgeon.
As their time together continued, Ogai performed various experiments on, and later with, her as it became apparent that she had attained enough setience to have wants and needs. Some of these experiments included:
- Introducing rat semen to Saya as a means to study and test her ability to reshape biological matter.
- He explains Arabic numerals to her and sees her ease in finding prime numbers instantly.
- Ogai allows her to read literature and notices she consumes knowledge with a voracious hunger.
Ogai, in his notes, does make various references to how he finds Saya's various forced mutations upon rats 'beautiful' going as far to call them 'art'. Later on, he would explain that he felt a paternal attachment to her.
He committed suicide for ambiguous reasons; most likely some time after Saya started living with Fuminori. If he commited suicide before Saya left, then she likely left due to his absence. The revolver that he used to kill himself was later used by Koji when he confronts Fuminori at the end of the novel.
Ryoko and Koji find his corpse in his secret bunker behind a false wall in a well. Ryoko collects his notes and later studies them to understand Saya's species. It seems that she finds a secret weapon, later found out to be liquid nitrogen, in the notes that is used to kill Saya in the Humanity Wins Ending.
In the Saya Wins Ending, it is revealed through Ryoko reading his notes that he killed himself in order to try and ensure Saya's success.
It is possible that he performed surgery on Fuminori in such a way as to intentionally make Saya look beautiful which he knew would ensure her happiness and success.
Ogai's notes also make direct reference to The Silver Key, linking the game's universe with that of H.P. Lovecraft.
He was a surgeon with flexible, borderline non-existent, morality; he worked at the university hospital.
He was obsessed with the occult and struggled to see weight in the consequences of reality.
Masahiko's appearance when he was alive is unknown. As a corpse, he still retains some gray hair, skin, and gums. His body wears dark gray clothes.