In Exceedraft E13, Kosaku and Hayato pretend to be loan sharks or gangsters hounding Ken to repay his debts. They’re dressed in red, green and blue, which some think of as the three primary colours. Yet for traditional colour theory, the primary colours are red, blue and yellow which are the signature colours of Exceedraft’s main trio.

Having them each wear a primary colour different from the one they're usually associated with indicates their co-ordinated teamplay even while in disguise and with two of them appear to gang up on their teammate. Them wearing outfits with the primary colours associated with modern technology, rather than traditional colour theory, supports a view of their mission as marking a step forward in their growth as an elite, high tech team.

Their outfits also aptly complements E13’s focus on the camera as the central piece of technology propelling the case. Together, red, green and blue form the "foundation of digital color" used to optimise images shown on screens. The article linked compares the differences between the Red, Green and Blue (RGB) additive colour model and the Red, Yellow and Blue (RYB) subtractive colour model:

For each member's disguise, the primary colour that stands out differs from their respective signature colour. Thinking about their disguise's dominant primary colour in relation to their signature colour clarifies their individual contributions for E13's case.

On a side-note, Tokusou Robo Janperson also has another trio appearing in matching RGB outfits. They are the villainous trio of Tatewaki Konzern, one of the evil organisations seeking to take down the show's titular hero. This show follows Exceedraft and is another Metal Hero show with Miyashita Junichi as a main writer.

In Exceedraft E13, the change in Ken's look is the most obvious since he almost always wears some yellow, which is his armour's colour. His disguise contains no trace of yellow, distancing him from his identity as Draft Keace. For his cover, he wears a jacket with a dark shade of green as he plays a darker version of himself. It possibly also symbolises him getting closer to the dark potential that his exceptional fighting skills present.

Kosaku and Hayato's disguises feature them having switched their signature colours with Kosaku (Blues) mainly wearing red and Hayato (Redder) mainly wearing blue. As Kosaku wears a large amount of his captain's signature colour, he appears more like the leader.

Kosaku taking up the leader's signature colour emphasises his role in Exceedraft as the member who specialises in disguises. It builds on his first effective use of disguises for resolving a case in just the previous episode (E12).

Before E12, we've only seen Kosaku's skill in taking on disguises in the outro. And while he's portrayed as the undercover specialist, he's relegated to playing a minor role for the undercover mission central to the Red Spade two-parter.

E13 thus has not just Ken, the one central to the episode's story and resolution, but also Kosaku coming into his own as a member of Exceedraft. Hayato himself shows a growing trust in his teammates as the Captain willingly takes on a supporting role for the mission.

To get back to the disguises of Kosaku and Hayato, notice the traces of their signature colours in the accessories for their loan shark outfits. Kosaku wears a blue sash over his red two-piece outfit while Hayato wears a tie that looks red with his blue suit.

These traces perhaps foreshadow the villains seeing through their act and discovering their identities as police officers. It could also represent the overlap of what's "real" and "fake" in the fabrication necessary for rescuing Ken's friend.

The traces of Kosaku and Hayato's signature colours in their disguises then suggest that like Ken, they remain true to themselves in carrying out their duties as upstanding police officers while putting on an act. Unlike the team's fragmentation during their last undercover mission to take down Red Spade, the trio presents a united front in E13 even as only one of them takes the lead for resolving the case.