Summer in Berlin is generally pleasant, with highs of around 25 degrees C even in the hottest months of July and August, but December to February is particularly cold, with lows below freezing.

Reference
Tokyo's climate
Weather Altas "Monthly weather forecast and climate Tokyo, Japan"
Retrieved June 5, 2020, from https://bit.ly/3dBbSTF

Berlin's climate
Weather Altas "Monthly weather forecast and climate Berlin, Germany"
Retrieved June 9, 2020, from https://bit.ly/2AQNyyQ

Berlin's humidity
Climatemps.com, Retrieved June 9, 2020, from https://bit.ly/303b3yE