Ritz Kobayashi is the Japanese manga artist and writer best known as the creator of the Saki franchise. Kobayashi made a professional debut with the short series Fatalizer, which ran in the magazine Comic Blade in 2004. Prior to achieving success as a manga creator, Kobayashi worked in an advertising agency and a game company, and also spent two years writing a serial column for a music magazine.

Kobayashi launched the signature work, Saki, in Square Enix's seinen magazine Young Gangan on February 3, 2006. The manga, which combines the sport of competitive mahjong with school club drama, remains in serialization and had released twenty-four compiled volumes as of July 2023. The series follows Saki Miyanaga, a high school freshman who initially dislikes mahjong due to family pressure but is recruited into her school's mahjong club and aims for the national championships.

The popularity of Saki led to a significant media franchise with multiple anime adaptations and spin-off manga. The first anime television series, produced by Gonzo, aired twenty-five episodes from April to September 2009. For this adaptation, Kobayashi is credited as the original creator. Following the main series, a spin-off manga titled Saki Achiga-hen episode of Side-A was launched in September 2011, with Kobayashi providing the story and Aguri Igarashi handling the illustration. This was adapted into an anime that aired from April 2012 to May 2013.

Regarding the specific work mentioned in the prompt, Saki Biyori, Kobayashi's involvement is as the original franchise creator. The manga Saki Biyori is a four-panel comedy spin-off written and illustrated by Saya Kiyoshi, which was serialized from June 2011 to March 2018. An original video animation adaptation of Saki Biyori was released on July 25, 2015, with production by Studio Gokumi, and the promotional materials for this OAD confirmed the return of staff from the main Saki anime. In this context, Ritz Kobayashi is credited as the original author of the Saki series from which the spin-off derives.

Further expanding the franchise, Kobayashi has served as the story writer for several other spin-off series. These include Side Story of Saki: Shinohayu the Dawn of Age, which began serialization in September 2013, and Toki, which began in June 2016, with both series illustrated by different artists. A third anime television series, Saki: The Nationals, covering the main manga's national tournament arc, aired from January to April 2014. The Saki franchise has also been adapted into live-action television dramas and films.

Kobayashi is known for a reclusive public profile, with minimal personal information disclosed. The creator's gender is not officially confirmed, and public appearances are extremely rare. In the manga industry, Kobayashi has achieved significant commercial success with Saki; as of 2015, the series was noted as one of the highest-selling active works in Young Gangan, with first print runs reaching two hundred thousand copies per volume. The cumulative sales of the main Saki manga volumes had reached 4.59 million copies by that time.