There's some serious breast expansion in a Japanese anime called The Qwaser of Stigmata. It occurs in episode 21, just a little under 8 minutes into the second half at this site. The storyline doesn't make a lot of sense. It's anti-Christian but in a way that accuses Christ of all kinds of crazy nonsense, as if the Apostles were vampires or something. But it has lots of big tits and some breast expansion, so whatever.
Gotta give it up on this one - it's a really good breast growth video morph of a scene from "Princess Lover".
I've had this image for at least a year but I've never seen anything else that's obviously by the same artist, and it's unsigned. Does anyone know if he's got other breast growth or breast expansion sequences floating around out there?
Miyuki Ayukawa by ~AngsTheWicked on deviantART
Miyuki Ayukawa is a very chesty character from Basquash, but in this work AngsTheWicked inflated her well beyond the norm.
Sometimes I wonder if the Japanese aren't merely from another country, but actually from another planet. Still, a video game that allows players to make characters' breasts grow is pretty cool. And yes, in Pai Touch!, that actually seems to be the main plot thrust of the game - give the girls huge tits. Here's the producer's web site.
[h/t: NinjaBunneh]