Heedless of Mama's warnings, a Japanese boy cannot resist playing at an ice-cold pond "filled with carp of bright colors.'' When he comes home, he is immediately treated for a cold, with a hot bath and rice gruel. His mother's attitude chills him more than the weather, though; he cannot understand why she seems to be ignoring him. Hearing a noise in the garden, the boy spies Mama digging up the pine tree that was planted when he was born. She brings it inside and decorates it with paper cranes and candles. It is a Christmas tree, the first for the boy, and the first in many years for his mother, who tells her son she comes from "a warm place called Ca-li-for-ni-a.'' The story is a poignant one, illuminated with finely drawn illustrations reflecting the serenity of a Japanese home and the quiet love between mother and son. Say (The Bicycle Man; El Chino ), who came to this country from Japan when he was a teenager, again exhibits a laudable sensitivity to Eastern and Western cultures--and to both the differences and the similarities between them. Ages 4-8.