The tachi created by Awataguchi Yoshimitsu who is well-known for making tantou. His name holds the meaning of "the only one" crafted in "one lifetime." He is acknowledged as the eldest brother of the Toushirous and affectionately called "Ichi-nii" by them. Although he can constantly be seen with a kind and calm smile, occasionally, he will show a somewhat sorrowful expression on his face.

(Source: Official site)