A Pink marked their fourth anniversary since debut by allotting volunteer time for disabled children.

On Sunday, all six members of the girl group trooped to the disabled children's facility in Gwangju, Gyeonggi Province, reports KPopHerald.

The girls spent their time interacting with and putting smiles on the faces of kids staying in the care facility.

The girls seem to have chosen to visit the disabled children's facility in observance of the national Disabled Persons Day on April 20.

Moreover, A Pink fans joined the visit in solidarity with the heartwarming act of public service. The girls then thanked fans not only with messages but with a new release for the song "Promise U" written by A Pink member Eunji.

"Promise U" is reported to serve as a new fan song for the group, updating the initial fan song "April 19" released back in 2012, notes KPopHerald.

A Pink's acts of public service show their humble side despite being touted as one of the biggest rising K-Pop stars in Japan. The Japanese publication Oricon Style named A Pink as well as powerhouse boy group EXO as two groups that hold promising futures as K-Pop artists promoting in Japan. It noted that while other groups tried to gain popularity through sexy concepts, A Pink took on a cute and innocent image that proved a hit among fans and led to wide coverage for the group among the country's magazines and TV.

On April 29, A Pink will be attending the Japan's Girls Award fashion show, one of the biggest events in Japan with more than 30,000 attendees expected.