Ojiichan wa Shounen TanteiGrampa is a Boy Detective; Ojiichan wa Shounen Tantei; Ojii-chan is a shonen detective?; Ojii-chan wa Shounen Tantei; おじいちゃんは少年探偵; 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 granddaughter. Hilarity ensues as he encounters weird new stuff and does silly blunders in his daily life with his granddaughter, Hikari.