Happy Birthday Chitose-kun

On the day of his birthday, university student Chitose Tada spent the day alone. In vain, he remembered a classmate from his high school days, Koutaka, a tall, cool, and athletic guy, who transferred to his school in the second year. Chitose thought he was an uncool guy, but when he learned about his true nature, he became attracted to him...
A memorial love story of a blunt boy and a complicated college student.

(Source: Homesha, translated)

Note: Includes one extra chapter.