Tantei-san, Rucksack Aitemasu yo

Ichinose Yosuke is a detective–inventor who runs a detective business while devoting himself to inventions, having taken over the work after his father went missing. He uses his family’s former hot spring inn, now closed, in the small rural town of Nishigaya Onsen entirely as both his detective office and living quarters. The place is filled with Yosuke’s bizarre and surreal inventions.
In fact, Yosuke once conducted research in the United States on converting negative emotions into energy and achieved remarkable success. After his return to Japan, Nishigaya Onsen somehow transformed into a slightly eccentric hot spring town where mysterious vehicles roam about.
Set in this unusual hot spring town, a steady stream of strange requests from highly distinctive clients pours in day after day, sending Yosuke racing around to solve them. He tackles countless oddball cases using unpredictable and outlandish methods!
(source : mydramalist)