"Tree in the Sun") is a Japanese manga series written and illustrated by Osamu Tezuka about a friendship between a samurai and a doctor in the final decade of the Tokugawa Shogunate.

The story is partly based on Tezuka's great-grandfather who was one of the Japanese physicians pushing for acceptance of Western medical practice at the time.

The title is a metaphor for the Tokugawa shogunate which is compared to an old camphor tree which has enjoyed the sunshine and shelter from the winds for 300 years, but is slowly dying because it is being eaten away from the inside by termites and gribbles.

[2] The story follows two young men whose lives intersect during the political turbulence and social upheaval in Japan in the time before the Meiji Restoration in 1868.

Dr. Ryoan Tezuka is a medical student attracted to the radical new of Western medicine under Kōan Ogata, while Manjiro Ibuya is a samurai who is a staunch supporter of honor and tradition.

Meanwhile, Manjiro rises through the ranks of samurai society and the shogun initially gives him the delicate task of managing a United States emissary and later to turn farmers into an armed infantry.

Rather than being set in an imaginary world, as are many of Tezuka's earlier works, historical context plays an important role for the action of the characters and for dramatic effect.

This was sparked by researcher Yasuaki Fukase, who wrote a thesis about his great-grandfather Ryosen Tezuka and sent it to the manga artist with a personal letter.