Let’s start this One Piece theory with Roronoa Zoro and Kuina fighting on a moonlit night in a remote village in East Blue called Shimotsuki. Translated as “Frost Moon“, the Shimotsuki clan also rules Ringo, a snowy region filled swords and graveyards where the legendary Samurai known as Ryuma Shimotsuki was laid to rest.

https://thiswriteguy.com/anime/one-piece/roronoa-zoro-shimotsuki/

0:00 - Introduction
0:23 - Roronoa Zoro Arrives in Shimotsuki Village
1:35 - Shimotsuki Clan
3:46 - Zoro’s Swords
4:59 - Hakumai and Ringo
6:02 - Zoro’s Lineage
7:47 - Yasuie Shimotsuki and Zoro
10:03 - Zoro’s Sword style and Isshin Dojo
10:45 - Roronoa Zoro is Ushimaru Shimotsuki’s Son
12:00 - Ushimaru Shimotsuki is Admiral Green Bull