He does some of the latter because some punks knocked over the flowers he put out for a cute girl ghost and comes home to his annoying father, the only one in the family who can't see ghosts, attacking him. His two little sisters, Yuzu and Karin, eat dinner, and Yuzu suggests that they stop fighting, while Karin points out that Ichigo has been possessed again.
The next morning, there's a story on the news about a mysterious explosion near their home, and Ichigo gets caught up in what caused it soon after: a monster is chasing after the ghost girl he was helping yesterday! Luckily, some kid in a black hakama shows up and kills the monster, totally ignoring him. That night, the kid shows up again in his room - preceded by a black butterfly.
And it turns out that Ichigo shouldn't be able to see her - she's a shinigami, and he's trying to find another monster nearby. Actually, they're not monsters, they're bad spirits called horou, and eek here it comes! It takes Karin and tries to run off, but Ichigo breaks the bonds that the shinigami put on him and runs after it. The shinigami tells Ichigo her name, Rukia, and that the only way they can defeat the horou is for her to kill Ichigo and transform him into a shinigami as well... So Ichigo becomes a shinigami high school student, with a sword larger than any Rukia has ever seen...