Boyfriend - he turns the ground into ice. Gustaf from The Seven Deadly Sins is a gentle, kind-hearted young man and the younger brother of Jericho. Frail due to illness, he remains emotionally strong, offering unwavering support to Jericho, encouraging her to pursue her dreams. His protective nature and bravery in facing his condition define his character. Though a minor figure, Gustaf's death deeply impacts Jericho, motivating her growth and shaping her interactions with others, especially Ban, throughout the series.