Source
The source for the Patch Notes is the official CN website for NIKKE. They were posted as the most recent news post a few hours ago.
Once the official English patch notes are released, we will replace our translation with the official one.
Summary
Since the patch notes are pretty massive, here's a summary of everything that's coming this week.
New SSR character - Winter Shopper Rupee
New SSR character - Miracle Fairy Anne
New SR character - Neve
New event - Miracle Snow
New coop event - Grave Digger
New game mode - Arena
New event pass - Colour Me Red Emma skin
New skins - Covert Nurse Maiden, Model Worker Brid, Sweet Holic Poli, Joy to the Nerds Exia
Bug fixes
New characters

Rupee and N102 will receive their alter version characters: Winter Shopper Rupee and Miracle Fairy Anne. We already showed their design and basic information in another blog post, but we also added them to the website today! Still, their skills will remain hidden until we got official confirmation about them.
Winter Shopper Rupee - check profile
Miracle Fairy Anne - check profile
Neve - check profile
Also, while the Winter Shopper Rupee banner will start on the 8th of December, the Miracle Fairy Anne one will arrive a week later. All three characters are limited, so they won't be added to the general pool after their banners and the event end. When will they return? Most likely the next year on Christmas.
New event - Miracle Snow
Miracle Snow event will consist of:
14-day login calendar,
story event - Miracle Snow,
story event - Eternal Memory,
mini-game - Gift Factory
After the maintenance on the 8th of December, both the first story event - Miracle Snow - and the Gift Factory mini-game will start, but the second story event - Eternal Memory - will start a week later on the 15th of December.
From what we know, both story events have different currencies and shops, so that's a lot of rewards coming our way this month! We will post guides for the events once they are released.
New coop event - Grave Digger
Coop is back and this time we will fight the dreaded Grave Digger boss!
Good luck all. We will need it.
New game mode - Arena
Well, PVP is here!
The mode was removed on release due to some controversies, but now it's coming back. The good side is that Arena comes with its own shop, so this will be another source of skill materials and gear.
New event pass
Looks like, on top of the current battle pass, there will be another one added to the game that will have Emma's skin inside. The price isn't known yet, but it is rumored to be around 30$.

New skins
Four new skins will be added to the game and you can buy them while the Christmas festivities are available.
Covert Nurse Maiden

Model Worker Brid

Sweet Holic Poli

Joy to the Nerds Exia

Bug fixes
Same as last time, the patch notes don't have the bug fixes and they will be added there only after the maintenance. So we still have to wait to find out what exactly will be fixed this week.