Sharing the Starry Sea

In the 3000th year of the earth's history, due to the war and entering the final stage of life, mankind reflected on its mistakes and woke up at the last moment in time, exhausting resources to find "endless energy". Under the influence of endless energy, human beings have mastered the power like magic, and later changed their name to "Devil Man", and their life span has been significantly increased. The heroine lost her mother in a war when she was a child. She became dull and followed the same path as her mother. There are more opportunities in the new school, and I have made new friends, one of whom actually has something to do with what happened back then...