Clever detectives for the win. Both series have to deal with investigations, and an ensemble cast of characters each with their own specialties. Tokunana is especially interesting because of the fantasy that comes into play. The character designs and art direction (such as background design, especially in Tokunana) in both seriee gives a similar atmosphere, and it keeps the series interesting. Both series also have an excellent cast, and Kenjiro Tsuda does a fantastic job as the main brain Ichinose, as Nakamura Yuuichi did with Banba. Plus their openings have similar animation, color design, and music! These two series share something in their essence, so if you liked the vibe of one, then I'm sure you'll like the other!