Same type of characters:
-main protagonist is a bit of an outcast (voluntarily in Hyouka, forced in I.Zero ) with good deductions skills who later falls in love with the
-love interest, who is a curious & extremely popular girl
-best friend of the m.c. is a cheerful weirdo
-best friend of the love interest is a tsundere
- Hotaro and Hachiman both are introverted, apathetic anti-social individuals;
- Fuyumi and Yukino are cold yet elegant, strong-willed and refined ladies;
- Eru and Yui are extremely cheerful, jovial and upbeat girls;
- Similar genres (Drama, Comedy, Slice of Life);
- Great characterizations for the main characters;
Both series are about a group of friends which are part of a club that every once in a while does some helpful stuff to other people or solves some problems to them, but for most of the time they usually do nothing but read and chat, both series focuses on the main character's school lives and both series have extremely similar protagonists, but unlike Hotaro which is nothing but a spoiled brat, Hachiman has his reasons to be unsociable, is well-written and has plenty of depth and development.
They both involve a guy and a girl with their friends investigating different cases, with hints of romance. The atmosphere is calm and intriguing at the same time in both. Difference - in Akuryou mysteries more involve the supernatural, unlike Koten-bu.