銀魂―ぎんたま―（Gintama）【21】

竜宮城へ向かう船が難破し、無人島へと流れついた万事屋一行。そこで見つけた謎の「箱」に触れ、突如銀時と桂が老人と化す！　「箱」に隠された竜宮城の陰謀とは…！？　他にも機械メイドの休日とか極道の真白い粉（？）も必見！！

A ship going to Ryugu castle was shipwrecked and a line of directors arrived on a desert island. Touching the mysterious "box" found there, suddenly silver time and Katsura turns into an old man! What is the conspiracy of Ryugu castle hidden in "box" ...! Is it? Besides that, you should also look for a machine-made holiday or a true powder (? It is!