Higekiri, “Beard Cutter”! So, cute story, but the Onikiri/Higekiri was gifted to Tsuna by Minamoto no Yorimitsu, also known by his nickname, “Raikou”. Beard Cutter comes from when Minamoto no Mitsunaka, Raikou’s father, performed the earliest recorded tameshigiri: Tameshigiri is the act of doing a “test cut” to test the quality and edge of a sword against a target. The target happened to be a criminal with a long beard, and the blade was so finely honed that is sliced right through the beard (and, uh, the neck) cleanly. Which probably made for interesting water cooler talk when Tsuna and Raikou were like “HEY YOU REMEMBER HOW MY FATHER BEHEADED SOMEONE WITH THAT SWORD” “haha yeah now it’s cutting oni’s arms haha” and you’re like “ok but can we lighten up the mood maybe” because they’ve been hogging the water cooler for 15 minutes and you really just want to quench your thirst so you can go back to do Heian accounting but these two keep talking about DBZ fights they partook of.
The sword also was known as Shishi No Ko, or “Lion’s Cub”, because apparently it just roared like a lion one night and everyone just accepted that it was a weird fucking sword and it just did these things.