AREA NO KISHI/ The knight in the area episode 01 anime

Believing himself to be inadequate as a scorer, Aizawa Kakeru serves as the manager of his school's team, while his brother Suguru shines as its ace, even representing Japan. However, Kakeru may possess a hidden talent that only Suguru can perceive, leading to frequent clashes over Kakeru's denial of his abilities. Tragedy strikes when Suguru dies in a car accident, and Kakeru sustains a severe heart injury, requiring a transplant. In a bittersweet twist, their parents donate Suguru's heart to save Kakeru. Joined by Seven, an old friend and Kakeru's crush, Kakeru embarks on a journey toward national and international championships.