Shoutoku Taishi

The story of Prince Shotoku, one of the most important figures in classical Japanese history, starting from birth, going over all the most important moments of his life: his devotion to Buddhism, his marriage to Suiko, who became empress in 592, …
He was famous in history for his work as a regent, under the auspices of his wife, for having started the first diplomatic contacts with the Sui dynasty in China and having contributed to the spread of Buddhism in Japan, with the construction of two famous temples: The Shitennou-ji and Horyuu-ji.

(source: shoujo-manga.net)