Just like Gen Urobuchi, Naomi Takebe, the producer of Gaim, was also interviewed in Hyper Hobby. She explains why the chose fruits and specifically why Kamen Rider Gaim is based on an orange. 

Hyper Hobby: How did Gaim come about?
Takebe: We wanted to do something with multiple Riders. Every Rider after W has only had 2 Riders and we wanted to break away from that. I mean, you have AKB 48 with multiple members, there’s also sports teams and so many other things. Having multiple members brings excitement on different levels. We slowly ventured into the Sengoku era and planned on having that as the core theme. Every Rider would be taking inspiration from that era. But it would be boring if they all looked the same.
HH: So that’s why their are based on different armors to give each and everyone their own personality. 
Takebe: Exactly, we wanted to give them different things that would set them all apart. Like making some of them into insects, or even birds. Although, Bandai eventually came to us and said “Fruits“, that became the center theme we worked with. You can still see some bird features if you look carefully.
HH: Ah, so Bandai wanted you to incorporate the fruits into the toys that we now know as Arms Change. 
Takebe: They liked what we did with Kamen Rider OOO, how everything could be easily swapped around. Gaim has a similar feel to that.
HH: While you wanted to do a show with multiple Riders and have the Sengoku era as the theme, Bandai wanted you to use fruits. Is that correct?
Takebe: Basically. The reason why we agreed on fruits was because we wanted to use something that has never been used before as its core theme.
HH: But don’t you think using fruits would be strange?
Takebe: Not really. We’ve already done a train Rider, we aren’t really worried about this at all. (laughs)
HH: I understand then. (laughs)
Takebe: The thing is, when you see Gaim you don’t exactly think of an orange immediately. It’s right there, but still somewhat subtle.
HH: Why an orange out of all fruits?
Takebe: We actually researched into what fruits were popular with the kids. Orange came out on top.
HH: Oranges, bananas, grapes and melons were the most popular then?
Takebe: More or less. We choose fruits that everyone knew for the main Riders. Melons are high commodity fruits too.
HH: Is Kamen Rider Zangetsu more important then?
Takebe: He’s certainly stronger than the rest.
HH: So the value makes him stronger? (laughs)
Takebe: He’s kinda like Ouja from Ryuki.
HH: Regarding Kamen Rider Griton. He’s more of a nut, why is that? 
Takebe: That’s because Gen Urobuchi said he wanted to put the locks in different ranks. He thought nuts would be a good idea. Just like in OOO, you had Cell Medals and Core Medals separating each other. In Gaim there will be fruits and nuts.
HH: Why locks then?
Takebe: In our early design meetings we had this sentence in mind “Opening a new world” and “Unlocking potential.” After some research we figured locks were the best choice. They’re something we’ve never used. At this point, we had no idea what the story was even going to be like.
HH: The Sengoku Driver does seem like fun with the locks.
Takebe: I’m happy that they are all using the same belt. It reminds me of Kamen Rider Ryuki. I also like the plate on the side that shows the Rider’s face.
HH: Since there are so many Riders, will they be fighting each other?
Takebe: They’ll fight on occasion. But some of them will help each other out.
HH: It’s a bit like in the Sengoku era, where they’d form alliances together.
Takebe: Yes, it makes things more interesting. While they were enemies yesterday, they are allies today. But the alliances aren’t  always perfect. Betrayal may or may not occur.
HH: How does it feel to be working with Gen Urobuchi?
Takebe: It will be interesting. I liked what he did with Puella Magi Madoka Magica. You can see things resembling the Heisei Riders, how they all had different reasons to fight.
HH: Had you ever met the man before?
Takebe: No, but we’d tweeted each other before. We finally met through a mutual friend. He had so many ideas, so I invited him to write for Kamen Rider. At that point, Gaim’s design was nearly complete.
HH: Was the dance team thing already decided at that point?
Takebe: It wasn’t actually. We had already planned on having different factions, but we weren’t sure how to do it. Until Gen suggested dance teams. He’s been doing a very good job at creating a colorful, vibrant and charming world. Gaim is set in a fictional city, just like W’s Fuuto, which gives us more room with the creativity. We’ve also gotten a lot of help from Gen’s company, nitro+, with the designs. Their monster designs are very unique.
HH: Regarding the cast, is it true that there were no auditions?
Takebe: Not entirely. Because of Gen’s complex scripts, it was hard for us to have regular auditions. We handpicked a few people we thought were capable of expressing Gen’s scripts, and had auditions with them.
HH: How many candidates did you initially have for the protagonist, Kota Kazuraba?
Takebe: We didn’t have any, right from the start we knew it was Gaku Sano.
HH: What do you feel about the main staff?
Takebe: It’s the perfect team. Since we’re looking to go back to the early roots of Heisei, like Kuuga, Agito and Ryuki, we recruited the veteran director, Ryuta Tasaki. Tasaki has worked on some of these shows. But we still want to create something new and unique, which is why we have a new writer that’s famous in the anime world.
HH: This will be a challenge for Tasaki too, won’t it?
Takebe: Of course, but he’s eager to work on Gaim, despite his busy schedule. Please do look forward to the unique combination of Kamen Rider and fruits!