Assuming you're right, then all the spies have been on at least one mission.
For two votes of fail to happen in the second mission after the addition of only one person. That means that either Otakebi was the second spy, or two of the original three members were the spies who voted for fail. Working on the assumption that I am a spy, then there's a 33.3% chance of guessing the second spy, just based on numbers. Keep in mind, I'm taking one assumption and then inferring other facts from that single point of data. I'm an obvious subject because I've been privately lying to people. But lets move on.
The spies need two NO votes to secure the win. That's probably unlikely to happen. Assuming my assessments have been true, there is one spy who has yet to act. To be safe, you remove all the people from mission two. Gyoin, Thief, and Otakebi have yet to be on missions. Based on my comments and assuming only two spies were operating in mission 2, there is a 33.3% chance of choosing a fifth member who is a spy along with whoever the spy was in mission 3. This also assumes that mission 3's roster had only one spy in it.
The statistically safest option is to choose one of those last members, and add them to the previous team as the fifth member.
May the odds be in your favour.