OC here is Symboli Friend, who in this artist's continuity is Rudolf's eldest sister and a former race uma who later became a senior trainer and an instructor for other trainers. Rudolf's trainer happens to be her student.
This year's Leading Trainer......looks like it's confirmed to be Trainer-kun, nee-sama.So my teachings have finally borne fruit. Quite a lazy donkey he was.By the by, did that kiddo say anything?Oh, is that so.