Yup, those heroes are his classmates. I think Hiro's classmates are here to highlight how inefficient and corrupt the Human Kingdom is.
It's 47 chapters in and THEY'RE BLOODY STILL AT THE CASTLE? It's probably intentional or the kingdom is that stupid. Their skill and profiency growth is probably really poor.
notes. 4 heroes were Summoned by the human kingdom, and hiro was indecently near by and caught in the teleportation. the 4 heroes consist of a over ignorant justice hero. his childhood friend athletic but not that smart. a friendly girl that goes with the flow. and the library quiet girl.
from the start hiro demands them to return him. but the king said that they cant. but the demon kingdom might. already hearing many discrepancy in his words, hiro took his leave. While half of the hero group also notice something off, but stayed with the group. the friendly girl and library girl. who noticed, but one did not care enough and the other was abit high on her imagination of the story`s that she was always reading came true.
Minor spoiler!@#$
Back in their world library girl already has a crush on hiro. watching him read in the library but she never really approach him. in her head. she was always thinking that hiro will comeback. like a White power ranger. stronger that ever. and joins the team.
@ShionVaynex I think that warrant a spoiler tags mate. I don't really care and welcome the spoiler (quite predictable actually) but some people may offended.