Everyone had formed the two leg parts of their armor, and Rika had twelve pieces of metal left, but no matter how hard she tried, she couldn't make the chest or the head part of her armor.
...
One day, after they finished training, Rika said, "It seems that from now on the amount of metal needed is much greater than before."
And Gen said, "Well, there's nothing we can do but keep accumulating our metal pieces until we can create our armor parts."
Rika then said, "You're right.", and so the four of them continued their training.
...
Some time passed, and Rika finished her armor. She needed twenty pieces of metal to form the chest part, and sixteen pieces to form her helmet, but for some reason, before forming the chest part, she couldn't form the helmet part, even though it used fewer pieces of metal.
As she finished forming her armor, Rika said, "Finally!"
And Guna said, "Congratulations Rika."
