Ojiichan wa Shounen Tantei, Ojii-chan is a shonen detective?, Ojii-chan wa Shounen Tantei, 我的爷爷是少年侦探
Basically, the teenage detective kiddo was frozen by some EVIL MASTERMIND PROFESSOR back in near-mid-1900’s, and gets unfrozen in the 2000’s by his (assistant's) granddaughter, Hikari. Hilarity ensues as he encounters weird new stuff and commits silly blunders in his daily life with Hikari.