So, my bets
Nezumi the leader is manipulating his gang to kill themselves, and he'll come finish the last one and keep the money for himself
He settled everything so that Anbo will be considered the culprit, and totally disappeared.
Nezumi is at the lodge as well. Hard bet, but I'll go for the travel influencer. She doesn't look powerful, her mouse avatar fits quite well for a girl, and she acted to make Anbo the culprit.
She knew very well the robbery victims, which explain how she knew everything. Maybe using them to rob someone powerful around her, and make them the culprits after killing them.
Now about Spica, she surely knew the Yakuza was from the gang, so all her talk was a plan.
The weird thing is that she seems surprised he locked her in, she should have knew he would do that.
The other weird thing is that, even though she's locked in with someone coming to kill her, she isn't scared at all. Like everything in her plan will still connect. Maybe she'll simply revert the Yakuza by making him realizing how he's manipulated.
And now the question. Did Spica came here cause she already knew everything ? Or did she learnt that only once there ?