[1] Oishi began his career at Studio Junio as an animator, but gained fame for his work with fellow directors Akiyuki Shinbo and Shin Oonuma at studio Shaft, where he directed the Bakemonogatari television series and its prequel film trilogy Kizumonogatari.
[4] Oishi and Oonuma were given important tasks early on, with the former directing many of the opening animations to their series including several for both Pani Poni Dash!
In 2007, Oishi got involved with Shinbo and Ryouki Kamitsubo's adaptation of Hidamari Sketch as both an episode director and storyboard artist, as well as one of the art designers.
[16] Oishi mentioned that one of the problems he had in making the film was his inability to draw storyboards while sitting at his desk at the studio, so he instead wandered around the town with the film scenario and a pencil in hand and he would write down frames and ideas as they came to mind, before eventually returning to the studio to draw the storyboards themselves.
"[19] Kizumonogatari chief animation directors Hideyuki Morioka and Hiroki Yamamura, and unit directors Toshimasa Suzuki and Yukihiro Miyamoto, all commented on Oishi's ability to create unique and thoroughly drawn-out storyboards, which Suzuki commented on the particular aspect of Oishi's sense of pacing and its contrast between Kizumonogatari and the earlier Bakemonogatari.
[21] After that, there was little word of Oishi in the animation production industry for several years until 2023, in which he contributed key animation to Undead Unluck (directed by Shaft-adjacent director Yuki Yase), and when a film compilation version of Kizumonogatari, titled Kizumonogatari: Koyomi Vamp, was announced for an early 2024 showing.
[22] Speaking in an interview, Oishi stated that he had been largely working on the compilation film–which features re-recorded dialogue from most of the main characters, a newly composed film score including some of the old music, and new cuts of animation–for the past several years.
[25] While working on Pani Poni Dash, Oishi attempted to experiment with references to other media, and in one of his episodes tried referencing a drawing of Bakanon's father from Tensai Bakabon by Fujio Akatsuka.
[26] However, he was scolded for its inclusion by producers and was told that it might be painted over; though, Oishi instead suggested changing the drawings to flowers, which eventually stuck.
[27] Oishi experimented with coloring in Hidamari Sketch, which he did art design work for across the series alongside Shaft animator Yoshiaki Itou.
According to Oishi, Shinbo's orders for the style of the work included limited range of camera "angles" and positioning for the Hidamari apartments and the individual rooms of the main characters.