Osamu Tezuka (1928-1989) accomplished much in his lifetime. He was trained as a medical doctor but his love for drawing manga led him in a different direction. Nicknamed the "Father of Anime" and also the "God of Manga," Tezuka is often considered the Japanese version of Walt Disney. He is credited with the creation of the "large eyes" style of Japanese animation and also created over 700 manga in his lifetime. In the US, his most famous creation is probably Astro Boy, originally called The Mighty Atom, a character who appeared in cartoon series in the 1960s, 1980s, and 2000s as well as an upcoming movie.
Kapilavastu, named for the birthplace of Buddha, is the first of 8 volumes published by Vertical in which Tezuka presents a chronicle of Gautama Siddhartha Buddha along with some fictional elements and characters meant to provide drama, add comic relief, and move the story along. Originally, this narrative ran serially in Kibou no Tomo magazine from 1972 to 1983 and was Tezuka's last great epic work. Although he was more of a humanist than anything else, Tezuka admired and respected Buddha and felt that his story was inspirational and important to be told. The official website of the book has character and plot descriptions for each of the 8 volumes.
Critics have commented on how readable the book is but also how modern slang and behaviors might detract from the overall narrative, how light the story is in regards to its subject matter, how Tezuka straddles the line between writing for adults and children, and how multiple sensibilities come to play in this work.
Tezuka's official website is here and contains links to the publishers who put out his works, but there is also an encyclopedic fan website called Tezuka in English.
For more information on Buddha, there are websites that sketch his life via written works and poetry, detail his teachings, and
place both into religious context.