Origin
Masuda Tokisada, better known by his nom de guerre Amakusa Shirō, was a 17th century Japanese Catholic from the Amakusa islands who participated in the Shimabara Rebellion against daimyo Matsukura Katsuie over heavy taxation and persecution of Christians. The rebellion was suppressed and Amakusa was beheaded at the age of 17, though Matsukura would subsequently be deposed by the shogun.
Design
The banner Tokisada carries is based off of the Amakusa Shirō's real-life camp banner (Japanese: 天草四郎陣中旗, Hepburn Amakusa Shirō Jinchūki) painted by Yamada Emosaku.[1] The text reads in Portuguese (the language of the Jesuit missionaries in Japan) Lovvado seia o sãctissimo sacramento (modern spelling: Louvado seja o santíssimo sacramento), meaning "Praised be the most holy sacrament"; note that Kaneko's drawing is missing the final o in the first word that is present on the real banner. This banner depicts a Communion chalice and host flanked by two angels.