I thought watching Hyouka...Wow. This is like Death Note so much.
Both resolve some mysteries. Process and composition are truly very similar.
The description is just consistent (Except DN's 2nd half), and most of them are convince.
Both Protagonist, Light and Houtarou. They are so intelligent, and solve many problems around them.
Houtarou seems like Poker face and Bluntness, but He is fervid and a good man at heart.
Their Partner, L and Eru. They assist Protagonists with other persons (Hyouka's Kotenbu members). However, L is only a bit different.
Main difference, DN's theme is incident society, Hyouka's theme is youth in school.