Ippon-Matsu was the owner of the weapons shop in Loguetown Zoro visited. He was the previous owner of two of Zoro's swords, Sandai Kitetsu and Yubashiri.

When he first met Zoro, he tried to rip him off by buying Zoro's Wado for less than what it was worth, until Tashigi entered the shop. His greedy attitude changed when Zoro tested his luck with the Sandai Kitetsu (he threw it up into the air, then held out his arm to see if it would be sliced off).

After being impressed by Zoro's willingness to test his luck against Sandai Kitetsu and its curse he gave him Yubashiri for free. Yubashiri was his family's heirloom, a sword passed down through his family from one swordsman to the next until it reached him. His willingness to part with the sword, he told his wife, was that he was simply passing on to Zoro his dream.

Ippon-Matsu made a guest appearance in the The Detective Memoirs of Chief Straw Hat Luffy TV special.

(Source: One Piece Wikia)