The Hilleberg Anjan 2 is actually a lightweight (1.8 kg packed) 3 season tent. However, I believe that this tent could also be used during the winter season if there are only light snowfall and no strong winds. I have not tested the Anjan in harsh conditions but I could imagine that it works in the Finnish forests if there is not much wind and light snowfall. Here you can see how the Hilleberg Anjan looks pitched on snow.
Also, I found it difficult to pitch the tent on frozen ground. Probably, fixing the stakes with stones or on trees would provide better stability. Nowadays, I am using the Hilleberg Unna and even so, it is only considered to be a one-person tent, I have used it together with a friend during winter by removing the inner tent. It’s possible to create some sort of vestibule inside the Unna but I would found a dedicated vestibule more comfortable on an extended trip.
Have a look here if you want to see how the Anjan 2 looks during the summer months.