Premieres July 4th. The new PV is here. Check out the ANN article for additional information. Synopsis from AniList:
Monica Everett, the Silent Witch, is the world’s only practitioner of Voiceless Magic, a veritable heroine who single-handedly fended off the Black Dragon of legend. However, the young prodigy is actually…super-duper shy! Yup, turns out she only learned Voiceless Magic to avoid speaking in public. Ignorant of this, the Seven Sages have placed her on a top-secret mission to guard the Second Prince. Can Monica keep it together as she contends with both social interaction and the evils targeting the young royal?
I can’t think of any right now with the exact same mix of tropes (timid, overpowered, school setting) but there are several with shy but overpowered main characters and a similar general “vibe”. “Lacey Longs for Freedom: The Dawn Witch’s Low-Key Life after Defeating the Demon King” and “Taking My Reincarnation One Step at a Time: No One Told Me There Would Be Monsters” are the first that come to mind.