It's not just a 3DS stylus. It's a beauty roller. You can use it to play 3DS games and massage your mug, because nothing says video games like rolling things on your face.
This face roller uses germanium, which apparently has semi-conductivity properties and is known for its healing abilities. So, supposedly, if you use this germanium face roller, you can strengthen blood vessels and make them less visible in your face.
Snake oil, maybe, but rollers like this are popular in Japan. The concept behind this is that people can massage their faces while gaming.
The Germa Roller Touch Pen for 3DS comes in three colors: grey, Black, and Pink. It's priced at ¥1480 ($20).
And before you ask, yes, really.
Germa Pen [JTT]