Death of Lisanna Strauss is an event that took place two years prior to the beginning of the series.
Prologue
Lisanna and Natsu are talking among each other when Happy complains that Natsu ate all his fish. Then, Mirajane and Elfman invites her to go for an S-class job where they are going to suppress the king of monsters, The Beast. Natsu is disappointed when he is being rejected by Elfman, who says that a man should protect his family by himself. After that, they go to complete their mission.[1]
Death
Elfman attacks Lisanna
Elfman uses Beast Soul: Full-Body Take Over to protect Mirajane from being killed by The Beast. However, The Beast's magical power was too great and Elfman loses his grip on reality. Lisanna and Mirajane are at the scene watching him. According to Mirajane, if Elfman don't come to his senses soon, he will be consumed by The Beast. Lisanna tries to revert Elfman but he hits Lisanna with great force, throwing her a great distance.[2]
Lisanna disappears
Then, Lisanna is shown in her last moments holding her sister's hand, though she actually didn't die. Mirajane is tending her wound when an Anima opens and takes her into Edolas. When she regains conscious, she finds herself to a different Fairy Tail Guild. Everyone at the guild believes that she is the Lisanna they knew, and welcomes her back with a smile. From their reaction, she deduces that their Lisanna has passed away. Lisanna tries to explain, but she couldn't say a word, so she pretends to be their Lisanna.[3]
Aftermath
After their sister's death, Mirajane somehow lost much of her Magical ability and her will to fight. Mirajane also behaves differently towards Erza. Her personality changed drastically from a very feared person to a loving and caring person who treats everyone with kindness. Elfman also cannot perform a Full-Body Take Over (until the battle with Sol as he don't want his sister to cry again).[2]
Edolas Elfman bids good bye to Lisanna
In the Edolas arc, when the Anima begins to take the living beings with Magic away, Lisanna begins to glow. Lisanna tries to explain, but Mirajane and Elfman of Edolas reveals that they already knew the truth. Elfman says their Lisanna, someone who's really kind, and thus she can't let her real siblings cry anymore. As Lisanna tearfully screams out their names, Mirajane asks her to give them their regards.[4]
Lisanna hugs Natsu
When Lisanna arrives in Earthland again, she is caught by Pantherlily, suspecting her identity. Natsu and other guildmates saw her, and they are surprised. Lisanna tells them the truth that she is not dead and hugs Natsu.[5]
Lisanna reunited with her siblings
Meanwhile, Mirajane and Elfman are visiting Lisanna’s grave, two years since her apparent 'death'. Suddenly, they are surprised to hear a voice they once knew call out to them. Turning around, their eyes widen at the sight of Lisanna running. All of them cries and hugs each other for the first time in two years.[6]