stick-to-itiveness; perseverance; radical (esp. one that tends to ionize easily); root; indriya (faculty of the body having a specific function, i.e. the sensory organs)
Examples (1 in total)
ハルくんは昔からこうなの、心根は凄く優しいのよ。
Haru's always been like that; he's very kind at heart.