Chasiba Katase, also credited as Chashiba Katase, is a Japanese manga artist best known for illustrating the supernatural mystery series In/Spectre. Katase's professional identity is primarily defined by this single, long-running project, which has become a significant work in the shōnen manga genre.

Katase's most notable and defining work is the manga adaptation of In/Spectre. The series began serialization in Kodansha's Shōnen Magazine R on April 20, 2015. After Shōnen Magazine R ceased print publication, the manga continued in Monthly Shōnen Magazine and on the digital platform Magazine Pocket starting in December 2019. The original story for In/Spectre was created by author Kyo Shirodaira, who first published it as a novel in 2011. While the original novel featured illustrations by Hiro Kiyohara, Katase took over as the illustrator for the manga adaptation, which closely follows Shirodaira's narrative. The success of Katase's manga led to a republishing of the original novel series with new illustrations by Katase, as well as a two-season anime television adaptation produced by Brain's Base, which aired in 2020 and 2023. In the anime's credits, Katase is recognized for the original manga and for the original character designs.

Beyond the In/Spectre franchise, there is no widely documented evidence of other original manga series or significant one-shot works created by Chasiba Katase. The artist's published body of work appears to be almost entirely dedicated to the ongoing In/Spectre series, which has been collected into numerous tankōbon volumes. The French publisher Pika Édition releases the series under the title Stranger Case, but this is the same work. Katase's role is consistently cited as the illustrator, with the story credited to Kyo Shirodaira. For the In/Spectre anime, Katase is also credited for original character design, indicating involvement in the visual conception of the characters for the animated adaptation.

The artistic identity of Chasiba Katase is therefore inseparable from the world of In/Spectre. The series blends elements of urban fantasy, mystery, and romance, focusing on Kotoko Iwanaga, a young woman who serves as a mediator between the human world and the realm of yōkai (supernatural spirits). The narrative is driven by logical reasoning and deduction used to solve bizarre supernatural cases, a theme central to Shirodaira's writing. Katase's artwork is responsible for bringing these elements to life, visualizing the sometimes grotesque yōkai, the series' more grounded investigative scenes, and the dynamic between its protagonists. The manga is noted for its detailed linework and expressive character designs, which successfully translated to the anime adaptation.

Chasiba Katase's significance in the manga and anime industry is primarily as the artistic force behind a commercially and critically successful modern supernatural mystery series. By 2019, the In/Spectre manga had over two million copies in print, and in 2018, it was nominated for Best Shōnen Manga at the 42nd annual Kodansha Manga Award. The series' success demonstrates the viability of a multimedia franchise built from a novel adaptation, with Katase's manga serving as the key visual blueprint that expanded the story's audience. While not a creator of original stories, Katase's role as the illustrator has been crucial to the franchise's identity, proving that a manga artist's visual interpretation can be central to a property's widespread appeal across different media. Information regarding Katase's nationality is reported as Japanese, but personal details such as date of birth, artistic training, and career before In/Spectre are not publicly documented.