Kyô no Kira kun

Ninon Okamura is an introverted high schoolgirl who cannot talk with anyone other than her parents and Kansai dialect-speaking pet parrot, Sensei, due to the trauma of being bullied when she was in elementary school. However, her life changes when her mother requests her to befriend her next-door neighbor and classmate, Yuiji Kira, who suffers from a heart disease and likely only has one year left to live. Ninon encourages Kira to abandon his lewd lifestyle and instead fill his life with happiness, vowing to always remain on his side. The two become fast friends and ultimately fall for each other, though both are aware that their relationship likely has no future. Read more on Wikipedia.