In Sagas, it's already told how old the main characters are.. but for Twin Dragonslayers the only thing given is that there was a four year time skip after the events of CH1!
The encounter with the Dragon Man.. during the storm of the dragons. (Four Years Ago)
Mio is between 17-18 around this time, since her birthday was the day after the encounter. We'll just go ahead and say 18.
Mia is 14.

There's no clear age for the Dragon Man but he's around nearly thousands of years old.

Yuta is 11 years old during his first appearance

Jin isn't really shown and his father isn't either but Jin is the same age as Mio, while his father is in his mid 30s.

Yuta and Jin's mother is around her mid 30s.

The Four Year Time Skip, Present Day
In the last two colored pages of CH1, we get to see a older Mio who is now 22 years old. Mia hasn't appeared yet but she is now 18.


Jin's official first appearance was in CH2, just like Mio he's 22 years old.


Yuta is 15 years old

The Phoenix Knight Brothers

Kenta is 26 years old

Shun is 20 years old

Both of Jin and Yuta's parents are in there late 30s, early 40s now!

As the story continues and more characters get further revealed I'll come back to this! Thanks for reading!