Nintendo's Japanese site revealed the file sizes for several of the launch titles on Nintendo Switch. With an internal memory of only 32GB (and possibly less with the OS), file size is a pretty big deal. Of the anticipated launch titles, Dragon Quest Heroes I + II is the full 32GB, but given the OS size, even Nintendo's site states that the game cannot be downloaded to the internal memory and will require use of an external SD card. The full list of sizes is:

The Legend of Zelda: Breath of the Wild – 13.4 GB

Dragon Quest Heroes I+II – 32 GB

Mario Kart 8 – 7+ GB

Puyo Puyo Tetris – 1.09 GB

Disgaea 5 – 5.9 GB

I Am Setsuna – 1.4 GB

Nobunaga's Ambition – 5 GB

Snipperclips – 1.6 GB

Granted, the internal memory space can be boosted with the use of SD cards of up to 2TB. Which is probably going to be a necessity for most Switch users. Unlike the other Next Gen consoles, the Switch will not require that even disc games need to be downloaded which will help you save space on your tiny internal drive. So if you want Dragon Quest Heroes, my recommendation is to pick up a physical copy.

All of these sizes correspond to the Japanese releases of the games, so it is possible those file sizes may differ for the western releases.

Despite Nintendo's continued statements that the Switch will have 32GB of internal memory, the fact that they tell you Dragon Quest Heroes requires an SD card makes me think the leaked videos of stolen Switch consoles are correct and we only get about 27 GB to play around with.

If you want to test out your Japanese, the information can be found on the main Nintendo Japan site.