Is zero actually a good guy

[Kudo Shuuchi]

I wanted to discuss this with someone for a while now, Furuya Rei is a good character who loves is country and ready to sacrifice his life for anyone who needs help and he does his best to provide information about the BO to the secret police department he works at, but he was ready to hand in Akai Shuuchi to the organisation he even told Vermouth about Conan's plan and it's all due to Vermouth being too scared to believe that Akai is alive and luck that the black organisation didn't know about Akai's fake death.

Akai is known as the Silver bullet in the organisation and everyone of the BO code-named members know about him and is scared of him (except Gin) even the BO's boss and yet Rei was going to hand him over to the black organisation.

[SeraIsBestGirl]

Zero (a.k.a Furuya Rei) is only in the Black Organisation working undercover as a Security Bureau Officer. He only hates Shuuichi Akai because of a misunderstanding, yet Akai decided to leave it at that and now Rei thinks he is the cause of an event and so, the extreme hatred for him. But, other than that, he is a good guy as he is only putting up an act.

[Detective Enola]

Zero (Amuro) is infiltrating the Black Organization as it is his duty as a Public Security Bureau officer and he only hates Akai due to a misunderstanding (see episodes 866-867).

[Hanna.02]

I don’t believe Furuya Rei is a good person, even though he would die for his country. He tried to kill Sherry (KaitoKid in disguise) in episode 701-704 “Bell Tree Express“. He was ready to kill her just to strengthen his status in the BO. In the end he didn’t succeed and it didn’t change his status, so there was no reason to kill her after all. But he still thought he succeeded and he didn’t care. If it wasn’t for Conan and KaitoKid he would have actually killed her.. So no i don’t think such a person is „good“. 

Yes, we shouldn’t forget that he was undercover, but she was still innocent. It was morraly wrong.

Bell Tree Express (Episode 701–704