Prince Alto
Prince Alto is Lady Diana's husband and Momona's older cousin. He's best known for being a former Prince Candidate who ultimately dropped out of the selection process—partly because, as fans often note, he simply didn't have what it took to be King.
Before the series begins, Alto proposed to Diana during a date at the Music Box Museum on Jewel Mountain. The two made an eternal oath together and discovered a Music Box that Luea had hidden years earlier. Their relationship was strong enough that when Alto decided to leave the Prince Candidate program, Diana chose to abandon her own candidacy and run away with him rather than stay.
Momona clearly has feelings for Alto, longing for him despite his marriage to Diana.
Content compiled by AnimeList.moe from publicly available sources.
