Step 1 : Introduction to the question "According to proverb, if March comes in like a lion, how will it go out?"
...March Comes in Like a Lion, is an ongoing manga series by Chica Umino, best known for Honey and Clover. It began serialization in Hakusensha's seinen manga magazine Young Animal from its fourteenth issue in 2007. Hakusensha aired a television commercial announcing the series on numerous Japanese television stations, also posting it on its official website. Thirteen tankōbon volumes of the series have been released as of March 2018. An anime television adaptation by Shaft aired between October 8, 2016 and March 18, 2017 on NHK, with a second season premiered on October 2017. A two-part live-action film adaptation was released in March and April 2017.
Step 2 : Answer to the question "According to proverb, if March comes in like a lion, how will it go out?"
Like a lamb:
The basis for most weather folklore is observations. While some are nothing more than rhymes or beliefs passed down through generations, many turn out to be accurate. At a time when people believed spirits, both good and bad, controlled weather, they tended to include ideas in their belief systems that weather and life should balance. Thus, if a month began with bad weather, it "roared like a lion." If by the end of the month the weather patterns calmed, the month ended docile, like a lamb. With March's weather patterns varying from late-season snowstorms to warming spring temperatures, it is easy to understand the lion-to-lamb comparison. Source: FarmersAlmanac.com