How to give Diane's heart to Dr. Ives

The process of sending Diane's letter to Dr. Ives is as follows: I received a phone call from Diane on my way back. In undertale's game, when King Esgore asks you if you are ready, you choose not to be ready and return to Metaton Hotel in the same way. On the way back, you will get a call from Diane and give a letter to Dr. Ives for her.

Undertale's game and peace strategy, after triggering an appointment with Effie, return to the laboratory, take the toilet elevator to the real laboratory, find four keys (bed, under the refrigerator, bathtub and sink), then turn on the power and take the elevator back to the enchantment.

I wish you a happy life. Thank you for your concern?