[1][2] Like other celebrated dramas such as the Maodori-hasi and Ibaraki, it is based on the legend of Watanabe no Tsuna and the demon of Rashōmon.
[3] The play is set in the context of the final phase of the Heian period, leading up to the rise of rule by the military (by samurai warriors like Tsuna).
[4] The title is a pun,[5] which involves the Rajōmon (羅城門) outer castle gate but Kanze changed it by using the kanji shō for "life" rather than the original jō for "castle"[6][7] (note that 羅城門 was originally read raseimon and 生 can also be read as sei).
It is one of the few Noh plays where the supporting waki (脇) rather than the normally leading shite (仕手) dominates the action.
Act 1 takes place in the dining hall of a general, but in Act 2 the waki character, Tsuna, climbs the Rasho Gate to determine the truth of a story that a demon resides on the gate top.