"０１２３４５６７８９" => [
      171, 120, 238, 171, 120, 239, 
      171, 120, 240, 171, 120, 241, 
      171, 120, 242, 171, 120, 243, 
      171, 120, 244, 171, 120, 245, 
      171, 120, 246, 171, 120, 247
  ]

  "～" => [171, 121, 252, 198]

Whoa. Literally just giving it "Ｐｏｔａｔｏ" gives thrice as much token count as the letter count, 18 tokens for 6 letters.