As always, Wikipedia answers all. The festival that saw people from local clubs dress up as demons and the like, and parade up the main street, must have been Fastnacht. The flags that decorated the village for the last few weeks and that occasion were taken down yesterday.
If you'll join me on a Wikipedia-sponsored journey of amateur comparative culture, here are selections from the Fastnacht Wiki:
An old tradition in Southern Germany, carnival is the time of the year when the reign of bad spirits of the cold and grim winter period is over and these spirits are symbolically being hunted down and expelled. ... Carnival — this combination of pagan beliefs and Christian traditions — can thus be interpreted as the symbolic preparation for a new annual cycle.
That Wiki also goes on to mention fasting, which I'm guessing may also be connected to Lent since the adoption of Christianity. Next up are some bits from the Wiki on Setsubun, a Japanese festival that occurs around the same time as Fastnacht.
In its association with the Lunar New Year, Spring Setsubun can be and was previously thought of as a sort of New Year's Eve, and so was accompanied by a special ritual to cleanse away all the evil of the former year and drive away disease-bringing evil spirits for the year to come. ... The new year was felt to be a time when the spirit world became close to the physical world, thus the need to perform mamemaki to drive away any wandering spirits that might happen too close to one's home. Other customs during this time included religious dance, fasting, and bringing tools inside the house that might normally be left outside, to prevent the spirits from harming them.
And now, some pictures of the costumes. A lot of them were taken as we were walking home very briskly because we were freezing. If you're going to join an outside activity, wear lots of down-filled clothes!
It was funny how the evil beings would pick on teenage girls by briefly kidnapping them in order to rub straw in their hair. Not unlike how children in Japan may be picked up by someone dressed as a demon for good luck—yes, even though it makes them scream. My favourite story related to Setsubun activities came from kindergarten. A friend of mine said she quite enjoyed the "oni power" (demon power) that lasted long after her son's school celebrated the festival, because she could easily get him to do things, you know, by threat of demons coming to get him.