Digimon: Born of Koromon and
Digimon Adventure 21
These early directorial efforts from Mamoru Hosoda feature a lot of elements that con be considered trademarks of his today: great framing of shots with interesting and meaningful character blocking, fantastic use of naturalistic lighting, simple and expressive character designs, along with believable and interesting animation, significant use of classical music, emotional climaxes, and a great understanding of editing.
One thing that really stands out, watching these, is just how well every scene flows. There are no awkward cuts or languidly lingering shots; every shot is exactly as long as it needs to be, it moves the narrative forward, and it's composed in an interesting manner. I think one thing that can be easy to miss sometimes is how the sound design contributes to good editing; Hosoda uses music really well here to tie each cut together, and even has the animation in some scenes moving in rhythm with the soundtrack. It's a really powerful tool when used correctly. I think Hosoda's greatest strength may be that he makes directing look much easier than it actually is.
When you consider that this was a kid's show meant to sell toys, some of things Hosoda does here are really crazy and far beyond the effort you would expect. The use of heat waves and fisheye lenses to depict Taichi's disorientation and existential crisis is quite beyond the bland visual design you expect from a show like this, not to mention the beautiful background art and realistic, high-contrast lighting. It's easy to understand, watching these, how his directing skills would catch the eye of the big names in the anime industry.