KUROKAMI The Animation - Season 1 Episode 2 Contract

Keita and Kuro encounters a Tribal End sent to capture her alive after the previous encounter at the ramen stand was deemed to be a failure due to the Tribal End's defeat at Kuro's hands. In the midst of the fighting, Keita is killed when his heart was pierced by the Tribal End's mysterious Exceed energy in an attempt to fight Kuro. To save Keita before he dies from his fatal wounds, Kuro decides to create a pact between them by exchanging their hearts after she was able to bring him to safety. Kuro was once more able to defeat the Tribal End by electrocuting him after she created the pact with Keita successfully.