User blog comment:Jinbe/The Shichibukai as kids - preview/@comment-4202826-20110808072753/@comment-3242083-20110808091018

In Volume 63 SBS Oda drew the Shichibukai as children. Kuma had pale short cut hair and was missing his bear ears and cybernetic enhancements he receives later on. He wore tattered clothing and wooden sandals carrying a heavy load of chopped firewood on his back while reading a book called "Ninokin". His depiction has similarities with Ninomiya Sontoku, a famous philosopher of the 19th century. Many statues portray him holding a book while he walks with a heavy load on his back.

So, it is PROBABLY a reference to that dude.