Harden

 is the Astarian blacksmith who forged the Guardian Hearts swords.

History
Twenty years ago, Harden was burning with patriotism so he poured his heart into creating the Guardian Hearts for the Astarian military. He wanted to see the swords in action so went to battlefield himself. However, while there he witnessed them being used to hunt a +Anima, Margaret, and Harden's reaction was to protect her.

Plot
Igneous Giesrieg approaches Harden to request he make more swords like the Guardian Hearts.

Later, Harden hears a commotion outside of his house and goes out to demand they stop. Igneous is pointing a sword at Senri, and Husky is injured, so he tells Margaret and the +Anima to go inside, and he carries Husky himself.

Inside, he explains that the Astarian military want him to reforge their swords, but he refused. Harden scolds Senri for using his bear claw so recklessly. Margaret lightens the mood by serving dinner and informing Harden that she intends to make the children her assistants.

The next day, Igneous and a few soldiers approach Harden's house with Nana tied up in a sack; they had caught her stealing an axe. In exchange for pardoning her, Harden agrees to reforge their swords. Harden is discontent with the situation and wonders whether he can do a good job having not made a sword in a long time. Cooro is disappointed that so much iron is going to be used for swords when there are a lot of people needing tools for daily life; this comment inspires Harden and he asks for the +Animas' help. Cooro, Husky and Senri exhaust themselves assisting Harden. After putting the children to bed, Margaret talks to Harden about how her Anima disappeared after she started living with him.

When the Astarian military return the next day, Harden presents them with boxes full of sickles, cleavers and carving knives. He explains that he put his heart into his work, and this was the result. After the military leave, Harden gives Cooro a hatchet. He and Margaret see the +Anima children off.

At the end of the series, the +Anima group return to live with Harden and Margaret.