Dramatic Irony: "She's not dead yet"
After Yuichi has told Mikage about his mother, Mikage replies, "What a life story." Yuichi answers, "She's not dead yet," indicating that he expects her to achieve even more extraordinary things in her life. However, this is an example of dramatic irony (albeit realized later by the reader, though they would certainly remember Yuichi's words) because, shortly after his statement, Eriko is murdered.
Dramatic Irony: Eriko's Letter
After Eriko's death, Yuichi is handed a letter from her. In her typical cheerful manner, Eriko has written, "One of these days we'll read this together and laugh." However, the actual result, which is the opposite of her expectation, is an example of dramatic irony.
Situational Irony: Mikage and Yuichi
Mikage reflects on Yuichi and his situation with his girlfriend. She realizes that "Because I wasn't in love with Yuichi, I understood that very well...if you're not in love with him, you can understand him" (29). This is situational irony because one would assume that you really know a person if you love them, whereas someone like Mikage who barely knows Yuichi would not have deep insights into his soul. This irony is Yoshimoto's way of stressing the unique relationship between the two characters and why they ought to be together.
