noun, na-adjective
pure and innocent through and through; single-mindedly pure
Describes a person or attitude that is completely sincere, naive, and unwavering in its purity. Often carries a nuance of being almost too innocent or straightforward.
彼女の純真一途な性格に、周りの人も心を打たれた。
Her pure and single-minded personality moved the people around her.
純真一途に夢を追い続ける彼の姿は、多くの人に勇気を与えた。
His figure, single-mindedly pursuing his dream with pure innocence, gave courage to many people.
Compound of 純真 (pure, innocent) and 一途 (single-minded, earnest). The exact historical derivation is uncertain, but the combination is straightforward.