"...not be... I said... that time... must not be set free... I said it... so often..."
Persona 2: Innocent Sin
Akinari teaches World History in Seven Sisters High School. His charming personality made him quite an idol among the students in Seven Sisters, including Junko Kurosu, a beautiful girl who is the very-first Miss Sevens, and Maya Okamura, the Japanese History teacher who admired him as a genius.
Akinari was troubled over the idea that the current world history is actually incorrect. He met with Tatsuya Sudou who had been rambling about voices in his head, and was rumored to be an arsonist. Akinari was convinced that Sudou was channeling the voices of Mayans, and with the cooperation of Okamura, they produced the Oracle of Maia. Intrigued by the revelations from the Oracle, Akinari worked on writing the In Lak'ech.
He married Junko after the latter's graduation. Junko was a famed celebrity, but she did not forget her love, and pursued Akinari. Together they had a son who they named Jun. However, the marriage did not prove to be a blissful one as Junko began to miss her life as a celebrity. Akinari and Junko fought constantly. When his home life got worse and worse, Jun began to hate both his mother and father.
She began spreading vicious rumors about him, weakening his hold on reality and partly aiding in his death; he died by falling in the Seven Sisters clock tower and being crushed by the gears. Nyarlathotep stole his form and used it to deceive his son into serving him; this Akinari was far more confident and less conflicted than him, making him a desirable paternal substitute.
After his death, rumors began to spread that his ghost haunted the clock tower, causing his spirit to appear to Tatsuya Suou's party when they visit the clock tower. The ghost Kashihara begged the party to stop the gears of the clock tower from moving once more.
His spirit, along with his wife's, was summoned to the eve of the final battle against the abomination to torture Jun with the realization he had a hand in destroying his own family. Kashihara apologizes to Jun, and states that while he had written the In Lak'ech to have the younger generation become ideal humans without suffering, he was a fool for believing that the people's hearts could create anything by relying on someone else's dream to find their own. Upon Nyarlathotep's defeat, he was revived and placed with no memory of the events in the new timeline.
Persona 2: Eternal Punishment
"World History teacher for seniors. Though strange, he is a kind teacher."
He returns in the second game, still happily married and oblivious to the events of the previous game. He states that he is a fan of Kismet's monthly occult magazine, "Moo", and says that while he used to write books like "UFO discovered Underneath City!", he's now taken to just enjoying them for fun.
Later in the game, he appears at Kismet Publishing, convinced that he's the editor-in-chief of Moo's office. If asked to by Maya Amano, he will tell her about the legend of the Ancestral Persona, how Kiyotada Sumaru rose to power with Wang Long and was slain by the samurai Tatsunoshin Suou, and that when he rebelled, the Ameno Torifune rose, along with an eerie castle being built.