If you loved Kaze to Ki no Uta Sanctus: Sei Naru Kana, try Mobile Suit Gundam: Cucuruz Doan's Island
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Kaze to Ki no Uta Sanctus: Sei Naru Kana
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Mobile Suit Gundam: Cucuruz Doan's Island
What they share
Both films are directed by Yoshikazu Yasuhiko, and they both carry the bittersweet, outsider, tender mood tags, and they sit in Animation / Drama territory. If that's the register that drew you to Kaze to Ki no Uta Sanctus: Sei Naru Kana, the second film will land in a comparable space — through a different lens.
bittersweetoutsidertender
What Mobile Suit Gundam: Cucuruz Doan's Island is
You pilot a mobile suit in a covert mission gone wrong, and then enemy forces attack, but the director Yoshikazu Yasuhiko leaves you with a desperate escape.