If so, if there's any chance you could stop by Tokyo Sky Tree, let me know. They're supposed to have some Nintama Rantaro cels and production materials on display as part of a 25th anniversary event. It costs 500 yen to get in though, so I can understand if you're not a fan not wanting to bother. But if you happen to be around that way and want to check it out and report back whether there was anything cool, I'd be forever jealous.
Information at the top of page five of the PDF here (in Japanese):
http://www.tokyo-skytree.jp/press/upload/2017031402.pdf