Rain was reported to have donated 100 million KRW (~$122,590 USD) to the research and development of a cure for ALS ('Amyotrophic Lateral Sclerosis', also known as Lou Gehrig's Disease).
According to allkpop, Rain shared the soft spot he has for the good cause as his agency Cube Entertainment CEO Hong Seung Sung is currently suffering from Lou Gehrig's disease.
He shared what this campaign means to him through his ice bucket challenge clip, "Getting to participate in the ice bucket campaign is especially meaningful [to me].
"My mentor and father-like figure, who helped me to debut under the name 'Rain' and made me who I am today, has been suffering from Lou Gehrig's disease for 3 years.
"I've always wondered how I should express that grace and gratitude. A cure for Lou Gehrig's disease is currently in development at a national university hospital. I want to donate for the good cause."
Rain also nominated Psy, Lee Byung Hun, and Megan Fox for the challenge.