The first character in her last name (美 means "beauty". The last character (樹 means "tree". Her name could also be written 幹 (tree trunk) or 神酒 (sake offered to the gods)
Her first name is written in hiragana, which has no special meaning. However, "sayaka" could also be written 明か (obvious) or 清か (clear)
Бревно же!Дерево!