Return

Ajax's room, Hazegroove mercenary squad building,

 The empty room which looked very peaceful, a portal appeared suddenly in the middle of the room.

From the portal, a young man came out.

Rather than saying 'came out,' the words 'threw out' would more likely suit the situation. 

That's correct. Ajax was thrown out by the suddenly appeared portal before it vanished from the room.

"Ouch," Ajax, who was thrown out of the portal, stood up slowly with pains all over his body.

"Finally, I am back," he cheered himself.

 He felt good to return to his peaceful room from all the things he went through in the Five elemental world.

'Ding,

 Mission name:- Escape from the Older Birdman is completed.

 Reward:- A new system feature is unlocked.

 Clearance rating:- A+(The host showed his wits and successfully completed the mission.)