TITLE: 弥生: 一万分の一なんですって [Yayoi: I heard it was one ten-thousandths]
AIRED DATE: 16th Oct, 2016


Hirano Toushirou finds a lucky four-leaf clover under the great tree. He wants to present it to the citadel's newly forged sword Uguisumaru, but due to the obstacles en route, things do not go as planned. At the same time, under the great tree, the Awataguchi Tantou reminisce about their yet-to-appear older brother. Knowing everyone's wishes, Yamatonokami Yasusada thinks of a plan.

taken from touken ranbu wiki