If you're looking for anime similar to One Piece Special 4: The Detective Memoirs of Chief Straw Hat Luffy, you might like these titles. All recommendations are made by Anime-Planet users like you!
Samurai Champloo is all about style, from the dj-style scratching scene changes to the hip-hop-inspired soundtrack to the eclectic character design. Mugen's fighting style is a funky meld of capoeira and limb-cutting, and Jin is the dramatic foil; he is all steel and old-school samurai style. What binds them together is the desire to test each other's abilities, and a promise to a girl named Fuu: to find the samurai that smells of sunflowers, who plays a pivotal role in her past. Together they travel through edo-era Japan, finding battle and comedy wherever they stop.
Not entirely the same in setting, though both anime shares the feeling of the out-of-time boisterousness and behavior of its characters. This can be felt especially when we think of the parallels beetween Fuu and Onami, both girl being "practical" to the fingertips, hot headed, blat, and familiar with many ways of not too nice moneymaking.
Sakamoto Ryuunosuke is the son of the president of the Kidou Shinsengumi Corporation, a company that deals with capturing all unregistered youkai. Ryuunosuke has been studying abroad and has returned to Kyoto with his youkai, Nekomaru, to join the family business; but with the company in debt and the arduous task of having to fight the Tsubame Squad – who believe that youkai are being robbed of their freedom – Ryuunosuke has his work cut out for him! With others in the corporation trying to set him up with a girl from the local restaurant, and obstacles from loan collectors to a giant Kappa hell-bent on revenge standing in his way, can Ryuunosuke succeed, or will the company just end up in even more debt?
While this may seem like an odd rec, bear with me. Though Kidou Shinsengumi Moeyo Ken TV is more supernatural, both anime are set in Fuedal Japan. Both are also a bit on the silly side and have a reasonable amount of action and general destruction. If you like this setting and enjoyed one, then you may want to check out the other.