Mystery! The Boy who Heals Zoids is the ninth episode of Zoids: Wild. It first aired in Japan on September 1, 2018.
A few different things happen this episode. Arashi arrives at a village that's hostile to Zoids, (many villages don't like Zoids since they are so dangerous, the ones featured so far have been abnormal in their acceptance of Zoids).
Onigiri and Arashi head out, but Penne doesn't follow them. They end up stuck in a bog and wile Kuwagas and Kabtors free them. They meet up with the boy and realise the Zoids are all injured in one way or another.
Onigiri tries to help, but it's revealed he's had a troubled past with Zoid Maintenance. Specifically the Gannontoise was harmed when he accidentally polluted a lake. In flashback it's seen Onigiri tried to care for the Gannontoise, but wasn't very successful. The Gannontoise chose to follow him on its own, acknowledging how much he cared for the Zoid.
Eventually the Death Metal forces show up, and they fight. Both Arashi and Onigiri use their Wild Blasts to fend them off. Penne was watching on the sideline.