In 2014, Ōishi's song "Kimi Ja Nakya Dame Mitai" was used as the opening theme to the anime series Monthly Girls' Nozaki-kun, and in 2018, his song "Otomodachi Film" was used as the opening theme to the anime series Tada Never Falls in Love.

He has also written songs for other artists, such as "Yōkoso Japari Park e" which was used as the opening theme to the anime series Kemono Friends.

[2] Following the band's dissolution in 2006, he started a solo career, beginning with the release of his debut single "Honoka Terasu" (ほのかてらす) on June 25, 2008.

[8] In 2011, Sound Schedule decided to reunite after a five-year break, with Ōishi returning as the band's vocalist.

[14] That same year, he released the single "Kimi Ja Nakya Dame Mitai" (君じゃなきゃダメみたい) on August 27;[15] the title track is used as the opening theme to the anime series Monthly Girls' Nozaki-kun.

[14] The group has since performed theme songs for anime series such as Overlord, Prince of Stride, and Hand Shakers.

[18] In 2016, Ōishi wrote the song "Yōkoso Japari Park e" (ようこそジャパリパークへ), which was used as the opening theme to the anime series Kemono Friends.

[20] That same year, he wrote the song "Eien Loop" (永遠ループ) by Ami Wajima, which was used as the second ending theme to the anime series Kuromukuro.

[22] In 2017, Ōishi released his seventh album Kariuta (仮歌), which included a cover of "Yōkoso Japari Park e".