The death of Leomon in previous chapters was not part of a massacre. This made his death tragic, outstanding, and memorable. Though not announced officially, this might be a symbolic act rather than having a specific grudge against a fictional character made by themselves. But here and now, every buddy appmon just died including that of the main protagonist. One of them resembles a lion. This doesn't mean they killed him again. This time they killed everyone. As an example, there might be a Tri leomon dying in the process of reboot. But it doesn't count as a real death of leomon. But if you like to kill leomon more than the staff do, feel free to kill him in all the massacres in the digital world. I think this is now what the fan of digimon really want from the staff and won't be satisfied with any Digimon media without a lion's death. But appmon killed just everyone including a lion-shaped appmon.
The fact that the chips vanished when the appli drives where destroyed, reminded me of the black appli driver. They seriously need to introduce him/her to us. Of chips need appli drivers to remain stable, the appmon chips of Cameramon, Sakushimon, Warudamon, Cometmon, and maybe Sateramon should be connected to an appli driver in order to remain intact after their defeat. Though Sateramon's might have a different fate as it was picked by Knight, the previous ones should have been retrieved by the black appli drive. Knight was not introduced yet when they were defeated and we didn't see what happened to their chips. They could simply show them breaking and reducing to scattered data like what happened here implying their demise, but their fate indeed remained a mystery.
Facts aside, that mysterious guy might be Yuujin with his bipolar personality. He can act differently in different situations and the appmon cemetry may be the place where he reunites with Mienumon and others. I still hope to see the seventh god appmon as a result of a fusion between Sleepmon's ultimate form and Sateramon since they are both very close to Knight right now. There might be still two places for Ai and Watson in this case. But this scenario is without doubt just wishful thinking and none of that will happen specially the Ai and Watson's part
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