xxxHOLiC, Sougiya Riddle Recommendations
Similar plots between the two. Both of the main characters are high school students being tailed by spirits, thus compelling them to seek help from a strange higher source. Watanuki becomes obligated to work with Yuuko in order for his wish to be rid of the tailing spirits be fulfilled. The theme also mirrors the plot relationship between Hayato and the Undertaker. Both Yuuko and Riddle are eccentric characters who emit an aura of mystery and wisdom into the pages. Xxxholic is, however, much more complex than Undertaker Riddle.