Ato is a lonely and sorrowful little boy trying to come to terms with the recent death of his father. His world brightens up when a weird clownish angel called Sunshine becomes his friend and gives him the most amazing gift he could've ever asked for.
However, just when he is beginning to feel happy for the first in months, he is shocked to learn he has been chosen to be a member of an age-old secret organisation called The League of Giant Slayers. But in order to assume this great responsibility, Ato must overcome his fears and embrace his destiny. Could he be the little Giant Slayer prophesied about centuries ago, who would mark a new era in the life of the league?