""It's not fair for her to force her own ideas on the rest of us! There must be so many things you wanna know, Kouichi."''"

- Ikuo's last words to Kouchi.

Ikuo Takabayashi was a student from 9th Grade Class 3 in 1998, and one of the "Deaths of June". His maternal grandparents, Kensaku and Keiko Numata, are owners of Sakitani Kinenkan. He's replaced by Suguru Yamada in the Live Action Movie.

Ikuo was a thin, fair-skinned boy of below average height, being one of the shortest boys in class. He had short greenish-brown hair, which was divided into two large locks between his forehead, green eyes, and freckles on his nose bridge. As a high school student, Ikuo does not usually wear the men's school uniform jacket; instead, wearing a dark blue vest over a long white shirt. He has some feminine features, such as curvy hips and long eyelashes; his voice is even a bit high-pitched. His design in the manga is completely unknown, since he was never seen, just mentioned by his classmate and good friend.

Ikuo used to be quite a quiet and shy boy, who didn't have many friends. He reveals in "Rough Sketch" that he wants to be a runner, but has a heart condition that makes that dream impossible. He also shows great courage: he is willing to tell Kōichi Sakakibara the reason why everyone was ignoring him and Mei, even though he knew what would likely happen if he did.

A quiet boy who sat in the back of the class, Ikuo was frequently absent from school due to his weak heart. In "Rough Sketch", he was among the students who welcomed Kōichi to Class 3 on his first day.

Later, he was seen in the background in "Blueprint", sketching with the others. He sits at the same table as Kōichi, San Watanabe, and Megumi Tatara.

Ikuo was seen in "Bone Work", where he walked home with a dark blue umbrella and a light blue backpack.

In "Put Flesh", Ikuo stared at Kōichi when he arrived with the rest of the class. He was seen in the background again, reading a book (what could even be a manga) and even resting by closing his eyes.

Ikuo was one of the students Izumi pulled into the all-class meeting to discuss her new countermeasures. In "Build Limbs", when Kōichi asked him and Yūya Mochizuki to walk home with him, Ikuo was willing to tell him the truth, saying how he didn't like how Izumi Akazawa was handling the situation. Before he could reveal anything, however, he suffered a fatal heart attack. He is one of the "Deaths of June."

Ikuo later appears in Kōichi's nightmare in "Body Paint", accusing Kōichi of causing his death, suggesting Kōichi felt guilty about it.

In the manga, his death is off-screen and is only mentioned by Yūya, who received this news in a phone call. Unlike the anime, in the manga, his death was the catalyst for the class ignoring Kōichi, rather than being caused by it.

Ikuo wasn't the typical popular boy in Class 3-3, but was close to many of his classmates, including:

Ikuo was one of the students who welcomed Kōichi on his first day at school. He even called Kōichi by his first name, which suggested that Ikuo considered Kōichi a close friend, despite just meeting him. When the two talked at P.E. class on the bench, he told Kōichi about his heart condition, and Kōichi supported him in staying strong and not giving up on his dreams. And when Ikuo suddenly felt a bit ill, Kōichi offered to help him, but Ikuo declined, which suggests that he didn't want to put more weight on Kōichi's.

Later on, in "Build Limbs", Ikuo and Yūya accepted Kōichi's offer to walk home together. When they did so, Kōichi started to ask questions as always, to which Yūya's replies were only that he doesn't have to know yet, which of course caused Ikuo to feel pity for Kōichi, and then even a bit of annoyance that no one wants him to know the truth. So then Ikuo collected all of his courage and told Kōichi his opinions on Izumi's way of handling the situation and the whole curse, which suggests that he trusts in Kōichi and is willing to tell him everything he wants to know.

But just before he could answer, Ikuo suffered a sudden heart attack and died. Kōichi was visibly terrified, so it can be inferred that he did care about his friend.

-I wish I could run with all my strength...

-So I guess, you have been running before..

''-I'm gonna.. Go to the nurse's office and lie down..''

''-It's just not fair. I have to say, I can't agree with Akazawa's way of handling the situation!''

-It's all your fault, Kōichi.