Platycodon is well known as Balloon Flower or Bellflower. This flowering plant is an easy to grow perennial plant and prefers to grow in full sun or partial shade area of well drained soil. The names of Bellflower and Balloon Flower are delivered from the bud shapes of the plant as you can see on these pictures (they are look like tiny balloons or bells). We call this flower as 桔梗(kikyou) in Japan and often used as girl name as you may already know from some Japanese anime.
Second photo is for Fuji White of Platycodon .