Karin was a gentle and caring figure for both Joshua and Loewe. She would always remain by their sides and support their dreams of becoming bracers, also vowing to protect her beloved younger brother as well as her lover. Karin had already dreamed of living her life out fully by loving Loewe and watching her brother grow up.
- Main article: Hamel Tragedy
However, on the night of April 23, S.1192, Hamel was attacked by jaeger dropouts. The village was instantly in flames and residents were cut down one by one. Loewe told Karin to take Joshua and escape the village, promising to meet up with the siblings later after he helped fend off the attackers. Karin fled the fire-infested village, taking Joshua by the hand with Joshua's dog with them.
Their freedom was short-lived, however, as a jaeger tracked them. The jaeger tried attacking Karin, but Joshua protected her. During the struggle, Karin was stabbed multiple times and eventually collapsed, still holding Joshua in her arms. Joshua was both enraged and scared, and decided to shoot the jaeger with his own gun, ending the fight between the Astray siblings and the dropout.
Loewe arrived at the scene when Karin had only a little time left in the world, holding her close and begging her to not die. Karin smiled sweetly like she always did and handed her harmonica to Joshua, telling him to grow up strong. She then directed her attention to Loewe asking him to watch over Joshua. With her last breathe, Karin thanked and told both her dearests she loved them.
- Karin is very similar to Rufina Argent as they are both the elder sisters of the secondary protagonists and have gentle and kind personalities.
- The last time Joshua had ever cried was when Karin died, until over 10 years later, Estelle Bright's love for him made Joshua break down into tears.
- Karin can be seen next to Loewe as he fades away after one of the final battles in Trails in the Sky the 3rd.