You're mostly right, but there's two problems here:

First off, we all curfewed together. If Lavi and Micah both woke up in the same place, the fight never would have made it to the aquarium or the onsen. Micah is a bit naive, but by now I think he understands what 'waking up when everyone else is asleep' means. The fight would have happened in the theater, or there would have at least been evidence in the theater.

Second, I think Lavi is still too injured from Thursday to have done a murder.