Science fiction warm therapy movie recommendation

Rating: 9.5

In the summer vacation of the second year of high school, Kenji, a weak mathematical genius, promised to work for Xia, a dull predecessor. So they came to Xia's hometown in Nagano. I didn't expect Xia's hometown to be a big family of 27 people.

Xia's great-grandmother Rong is a Warring States family handed down from Muromachi era: the head of the family in the array, the head of the family. The whole family came from all over the country to celebrate their 90th birthday. At this time, Xia suddenly asked Kenji to pretend to be her fiance.

So, after Rong Qiang stayed, Kenji had to stay in the country for a few more days. Facing the warm hospitality of relatives in summer, Kenji is under pressure to play the role of fiance. Then one night, he suddenly received a short message with mysterious numbers in it. Kenji, who is good at mathematics, immediately fell in love with these numbers and tried to interpret them. ...

The next day, the world changed greatly. The mysterious figure who deceived Kenji threw the world into chaos. "Everything is borne by our family!" Under Rong's command, Kenji, Xia and the people in the array United to fight against the world crisis together. ...