Instructions
Speak to all characters whose relationship bars you have maxed out. Each character converses with you a little bit, and then the game asks you if you wish to return home after speaking to everybody. Choose "No."
Continue playing the game as normal until you go to Junes. Walk up to the elevators and press "X." The game tells you that there is no reason for you to be here, and it again asks if you wish to return home. Choose "No" and attempt to open the elevators once more. The game will prompt you about why you are attempting to enter the elevators. Select the option that you still have business in Junes, and the main character appears, beginning a cutscene.
Continue through the game until you reach the Samegawa Flood Plain. Speak with both Nanako and Dojima. They will redirect you to the Velvet Room, where you must go next.
Speak to Igor once you reach the Velvet Room. He gives you the Orb of Sight.
Leave the Velvet Room and wait for the cutscene to finish. Head south and speak to the attendant, triggering another cutscene.
Return to Junes and interact with the television. This causes you to enter the television, and you must speak to Rise to trigger the final boss.
Defeat the final boss to access the true ending. Defeating her is just like the previous bosses you had to fight. Keep only your best weapons on you and heal yourself whenever your health is low.