Akai Giwaku (2005)

Akai Giwaku 2005 / 赤い疑惑 2005 / Red Suspicion , Red Misgivings , Red Confusion

Sachiko is the 17-year old daughter of radiotherapist Professor Oshima. After exposure to radiation in the hospital, she develops leukemia. As if that was not enough trouble for one lifetime, Sachiko discovers that Oshima is not her real father, and that her boyfriend is really her half brother. (Source: DramaWiki)