Yousuke Tamori, also credited as Yohsuke Tamori, is a Japanese manga artist and original creator, primarily known for the fantasy franchise PopoloCrois. Born in 1951, Tamori is a graduate of Keio University. He began his professional career as a creator in the late 1970s, making his debut in 1978 with the manga series Popolocrois Monogatari. This initial work was first published in Japanese periodicals such as Dakkusu and Pafu, a women's magazine. The series later began serialization in 1981 in the Asahi Shougakusei Shimbun, also known as the Asahi Elementary Student Newspaper, a subsidiary of The Asahi Shimbun Company. This serialization in October 1984 is often cited as the official start of the PopoloCrois series.

The PopoloCrois franchise stands as Tamori’s most significant and enduring creation. It is a fantasy media franchise centered on the adventures of a young prince named Pietro in a fairy-tale world. The title is a portmanteau of the Italian word popolo, meaning people, and the French word croisé, meaning crossing. Beyond its origins as a manga, the franchise has expanded into several role-playing video games, two anime television series, and a series of novels. The first anime adaptation, titled Popolocrois Monogatari, was broadcast on TV Tokyo for 25 episodes from October 1998 to March 1999. A second anime series, PoPoLoCrois, followed on the same network from October 2003 to March 2004, consisting of 26 episodes. These adaptations brought Tamori’s characters and world to a wider audience, cementing the series' place in Japanese popular culture.

In the video game medium, Tamori collaborated with Sony Computer Entertainment, which released the first PopoloCrois RPG for the PlayStation in July 1996. The series continued with multiple sequels on the PlayStation and PlayStation 2. In 2005, a compilation version was released for the PlayStation Portable, which also became the first game in the franchise to be released outside Japan. Tamori has been directly involved in the adaptation of his work into games, stating that the concept for the game’s dramatic, animation-like presentation was influenced by a pilot film created for a potential anime project. His artistic identity is closely tied to a storybook aesthetic, emphasizing a 2D visual look reminiscent of a picture book, which he has identified as a core strength of the series. The general themes across his work include love, compassion, and racial equality, often exploring a coming-of-age narrative focused on the protagonist Pietro’s growth from boyhood to adolescence.

In addition to the PopoloCrois series, Tamori has created other manga works. These include Unreasonable NekoMaru, which also spawned a spin-off titled Unreasonable NekoMaru Gamebook, as well as Maihime Gomen, Magic Cat Damon, and UFO Kamen (Masked UFO). Later in his career, he collaborated with illustrator Atsuko Fukushima to produce a trilogy of PopoloCrois spin-off novels called Maya Mensis Aureos, published by Kaiseisha starting in 2013. Tamori also co-created a prequel novel, PopoloChronicle, in 2015. His industry significance lies in the successful, long-running multimedia nature of the PopoloCrois franchise, which he originated as a manga and which was later adapted into anime and video games. He has also participated in crossover projects, such as the 2015 Nintendo 3DS title Return to PopoloCrois: A Story of Seasons Fairytale, which he co-produced with Yoshifumi Hashimoto, the producer of the Story of Seasons franchise.