It's basically a fantasy series with magic, instead the only ones who can use magic are traps. The series revolves around three brothers, Rio, Noa and Rei Olmsted living on Olmsted Island who are at the age where they're just about to start using magic.
Porte Tricolore is a completed manga by Minase Seri, first published in 2012. It blends action, comedy, boys' love and fantasy. You can read all 5 available chapters of Porte Tricolore online for free on MangaPulse; the newest is Chapter 5, added 2018-03-27. The series is finished, so you can read it from start to end in one go.