[3] In 2007, he participated in the Lingua Comica Project[4] promoted by the Asia-Europe Foundation (ASEF) alongside various Asian and European comic professionals including Sarnath Banerjee, Gerald Corridge and Kôsei Ono, among others.

In 2017, he began writing and illustrating Umami, a webcomic released through Panel Syndicate, which tells the adventures of two cooks in a fantastic world, and that won the Eisner Award in 2019 for Best Digital Comic.

In recent years he had worked as an illustrator for L'Oréal China, the Spanish brewery Mahou, Judd Apatow, Marvel Comics, the Japanese rock group Grapevine and NHK Broadcasting Japan, among others.

In addition, he is the author of the art direction of the video game prototype Twinbee LOOP!, winner of the Konami Action & Shooting Contest in 2012.

[9] His latest work, Immortal Sergeant (2023, Image Comics), brought back together with Joe Kelly to create a road movie in which a veteran inspector sets out with his son in search of a murderer.

[10] That same year he collaborated with Alyssa Wong on Sparkle & Shine, the first story featuring the Venom magical girl Necroko, which gathered a very positive reaction from readers.

[11] As a teacher, Niimura has taught workshops on comics and manga at the University of Salamanca, Casa Asia, and the Japanese House of Culture in Paris, among other centres.

In addition to this, on the idea of publishing Umami as a webcomic, the author says: "There is much more fluid and unfiltered communication between the artist and the reader that is priceless and that helps us stay motivated".