The 20 year-old centre-back spent the recent campaign with sister club Girona where he developed into one of their standout defensive performers despite their final-day relegation.
Manchester City already possess a well-stocked backline after conceding just 35 top-flight goals last term, a record bested only by domestic winners Arsenal.
The anticipated arrival of new manager Enzo Maresca to replace Pep Guardiola continues to drag on, but the squad will require minimal adjustments this summer.
This managerial transition provides a clean slate for returning fringe players like the young Brazilian who will look to make an immediate impression during pre-season.
Reis is scheduled to join up with a depleted squad for the upcoming promotional tour of Hong Kong which is scheduled for the end of July.
Sixteen senior Manchester City players involved in the ongoing World Cup will be granted extended rest periods once their participation in the global tournament ends.
Media reports coming out of Spain recently suggested that Barcelona were preparing an offer for the player after monitoring his positive progress in La Liga.
Club sources have firmly dismissed the Spanish transfer links as nothing more than speculation, confirming the current plan is to keep the defender in Manchester.
The Premier League side originally spent twenty-nine point £6 million to sign the highly-rated prospect from South American side Palmeiras back in January 2025.
While fellow arrival Abdukodir Khusanov established himself as a regular first-team starter, Reis managed just four appearances before heading out on loan to gain experience.
Then-Girona coach Michel came to heavily rely on the defender who initially struggled with consistency and physical duels before adapting fully to the requirements of the league.