Joh-on's Death - S1.E28

One morning Erin receives a letter from Joh-on's son stating simply that Joh-on passed away from heart disease. Erin becomes sullen and sad, but acts strong in front of Lilan. Professor Esal and the returned Tomura see that Erin is suffering. Esal decides to take her on a trip to Joh-on's hideout when they were still students. Erin then comes to terms with Joh-on's death and promises to live a life that will not sadden Joh-on. At the end of the day, Erin says to Joh-on's ghost, "Thank You... Dad.