Hera asked the detail of the case from Yuda. As We know, Marin already knows the detail. I think Hera could be someone else who never appeared before. Or could she is Reika? That flower box quite familiar. Well, that's mere speculation.
@Ynneja
You add the @ sign in front of the user name.
Back to the topic. I hope there won't be the same old plot twist like your comrade works for your enemy. The old Kindaichi cases managed to do just find without that trope. Besides, Kindaichi seems damaged despite his carefree clumsy exterior.
They kinda did it with Senke, remember? In the 2nd series. Sure he wasn't as recurring as Reika or any of the other recurring cast but he was a recurring in the 1st series.