The entire time Tsuna and Hibari work through all the training that comes with trying to be an actual Pilot others are working and interacting with and beside them.
There's a set of twins with purple-blue hair. One is female and has an eyepatch. The other is male with one blue eye and one red. Their names are Chrome and Mukuro. Mukuro kind of creeps Tsuna out, which Hibari doesn't like. (Tsuna will later wonder and have it confirmed in their next Drift if that fact had influenced Hibari's instant dislike of the other boy.)
The next set of Pilots are Ryohei- someone both Tsuna and Hibari recognize from their years in school at Namimori- and Lambo who is sixteen and the youngest recruit in the Program. Tsuna later finds out that the boy was a certified genius and earned his way in early only to be lucky enough to find a Drift Compatible partner in Ryohei almost immediately.
The third set of trainees they worked with also contained someone Hibari and Tsuna recognized from school- one Yamamoto Takeshi, their old Baseball Idol. He had had a wakeup call of his own back when the Kaiju had first attacked. His father had been hurt. The man had recovered thankfully, but it seemed to wake something in Yamamoto much as the attack had woken something in Tsuna, and he had buckled down as well. His partner was a temperamental silver haired male named Gokudera Hayato. Tsuna didn't know him, but Yamamoto was Tsuna's friend-they had helped each other back in Namimori with their grades being so horrible and improved together- so Tsuna figured he soon would. (As soon as the four of them- Tsuna, Hibari, Gokudera and Yamamoto- had free time at the same time anyway)