If you loved The Tunnel to Summer, the Exit of Goodbyes, try Persona 3 the Movie: #2 Midsummer Knight's Dream
A bridge between a film you've already seen and one most people haven't. Persona 3 the Movie: #2 Midsummer Knight's Dream has roughly 5.8× fewer votes than The Tunnel to Summer, the Exit of Goodbyes — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.

The Tunnel to Summer, the Exit of Goodbyes

Persona 3 the Movie: #2 Midsummer Knight's Dream
What they share
Both films are directed by Tomohisa Taguchi, and they both carry the bittersweet, foreign gem, tender mood tags, and they sit in Animation / Fantasy territory. If that's the register that drew you to The Tunnel to Summer, the Exit of Goodbyes, the second film will land in a comparable space — through a different lens.
What Persona 3 the Movie: #2 Midsummer Knight's Dream is
Psychological drama meets anime fantasy. Makoto rebuilds his life with newfound allies. Delivers coming-of-age angst.