So I don't forget
Yuki;
Uses last name-san almost exclusively.
Exceptions
Paru-senpai
Linda
Miyu-chan
Miyoko
Canaan kids: Last name (Akimoto, Matsumoto) except for Yui (Who gets, as his student, Shirosaki-san when he can break the habit) or when he's trying to calm them down and not actively tsunning (First name-san).
Makoto: Swings between Hanejima-san and Makoto-san depending on his level of tsun vs dere at the time.
Everyone else: Currently last name-san.
Saburo:
Uses first name with no honorifics most of the time. If he uses a nickname, it's likely to annoy you, but it isn't actively malicious. If he upgrades to -san, it means he wants to burn your house down. If he starts calling you Doctor then he wants you to be tied up in the house while it burns.
Sakura
First name-san except if she gets to give them nicknames or she finds them super-cuuutee.
Uses last name-san almost exclusively.
Exceptions
Paru-senpai
Linda
Miyu-chan
Miyoko
Canaan kids: Last name (Akimoto, Matsumoto) except for Yui (Who gets, as his student, Shirosaki-san when he can break the habit) or when he's trying to calm them down and not actively tsunning (First name-san).
Makoto: Swings between Hanejima-san and Makoto-san depending on his level of tsun vs dere at the time.
Everyone else: Currently last name-san.
Saburo:
Uses first name with no honorifics most of the time. If he uses a nickname, it's likely to annoy you, but it isn't actively malicious. If he upgrades to -san, it means he wants to burn your house down. If he starts calling you Doctor then he wants you to be tied up in the house while it burns.
Sakura
First name-san except if she gets to give them nicknames or she finds them super-cuuutee.