【調査結果からの考察】
●ゾロは霜月牛マルの孫である（年齢から牛マルとゾロの間にもう一世代）
●牛マルの子供はコウ三郎と共にシモツキ村に移住
●牛マルの子供は移住後にゾロが生まる。その後にワノ国へ戻った
●康イエと牛マルは先祖は同じだが、康イエのルーツにはリューマはいない
●たしぎとスモーカーもやっぱりワノ国にルーツがありそう


ONE PIECE Research Report
- family tree(Kouzuki Family & Shimotsuki Family) -

<Possible considerations from the research report>
- Zoro is the grandson of Shimotsuki Ushimaru (another generation between Ushimaru and Zoro in terms of age).
- Ushimaru's child moves to Shimotsuki Village with Kouzaburo.
- Ushimaru's child will have Zoro after they migrate. After that, I returned to Wano.
- Yasuie and Ushimaru have the same distant ancestor, but Asuie's ancestor does not have Ryuma.
- Tashigi and Smoker also seem to have roots in Wanokuni.