Main character in this film, Mai, has a handicapped brother, who is totally deaf, called Dai-Chan. He is like a younger brother for Mai yet he is actually her older brother because Dai-Chan always asks Mai to hold him up with smiling all over. 
One day, an elementary school Mai goes to and a handicapped school Dai-Chan goes to start to communicate each other. And then, Mai's class mates started to make fun of Mai and draw a funny portrait of Dai-Chan on black board in the class. Mai gets shocked and hurt at that mischief. And moreover, their mother gets sickness at the same time. That's why Dai-Chan should enter in an orphanage for handicapped children; however, Mai really wants to take care of him by herself, so she tries to stop it. 
This story is written about a love of family, close bond, and relationship between human and human. We definitely have a common warm heart and a moment we have to use it with honest feeling. This film could remind us some important things we should never forget about our life. 
(Source: AniDB)

Dai-chan, Daisuki.