Guide from VivaJerry at 24 Jul 2023. Link below.
https://www.trueachievements.com/a381461/the-truth-in-your-h...On March 20 you'll be prompted to visit all your maxed out social links. Do so but then do NOT go back home even when prompted. Instead select “no” and instead, head to the Junes food court.
After meeting around the table in Junes, go to Samegawa Flood Plain Riverbank and talk to Dojima and Nanako. Then, go to the Central Shopping District South and into the Velvet Room. Igor will give you a key.
Now go to the gas station at the bottom of the central shopping district and talk to the attendant there a few times to bring you to the final dungeon of the game and it's true ending"