[
  {
    "yen_per_ball": 120,
    "balls": 112,
    "amount_yen": 13440
  },
  {
    "yen_per_ball": 50,
    "balls": 907,
    "amount_yen": 45350
  },
  {
    "yen_per_ball": 20,
    "balls": 1096,
    "amount_yen": 21920
  },
  {
    "yen_per_ball": 10,
    "balls": 1645,
    "amount_yen": 16450
  },
  {
    "yen_per_ball": 5,
    "balls": 818,
    "amount_yen": 4090
  }
]