So far I think I got the clue of everything about Satokoâs actions in Gou/Sotsu. They all must be tied to her trauma past. In fact, she just wants to take revenge on her sufferings in the past. But, why does Rika become her main target of all those things?
Gou/Sotsu-Satoko is still trapped in her child-self with all the bad memories from the past, which is why she has been thinking that no one treats her well beside her best friend, Rika.
She is still putting herself in a situation that everybody in Hinamizawa mistreating her, including her aunt and uncle. She knows Shion and Satoshi love her, but she must have a bad experience about Shion torturing her in the original show, and Satoshi had abandoned her for a whole year during his coma. She also doesnât think any other friend in the group accepting her like Rika (as you may notice, the OP of Sotsu shows Satoko seeing them all in a creepy smile and Rika isnât among them), Rika has always the only best friend who stayed with her during the good times in the past.
Therefore, it must be the reason that Satoko canât bear the pain to see Rika betraying her of all everyone else. Seeing her last hope slipped away triggered Satoko doing at any mean to keep her happiness alive.











