Just about the whole gosh-darn movie, as part of its polar opposite dynamic with Grave of the Fireflies.
Two moments that stand out for this trope are when Mei first meets Totoro and falls asleep on its chest, and when Totoro finally realizes what the umbrella does.
And how he continues holding the umbrella over his head even when he steps into the Catbus? That was pretty adorable, not gonna lie.