First off, Nintendo is a very conservative company and are probably not going to forecast a 25% increase in operating revenue at the begining of the year; they're most likely going to start at 5%, increase their projection to 10% after Q1, increase their projection to 15% after Q2, increase their projection to 20% after Q3, and report a 25% increase in operation revenue at their fiscal year end.
On top of this they're anticipating quite a bit of growth even though they're selling about as much Nintendo DS and Wii hardware as any console has ever sold, and their previous year had the release of (what will probably be) several of Nintendo's best selling games ever; as well as slow and steady sales from games released over the past several years.