There was once a site on the clear side of the Internet known as Fundatecity however; one user in particular was different than the others. Her username was アレクサ which many of the users said was kanji for "Alexa" so we'll just call her that. 
It began on a cold January morning in the mid-2000s when a username appeared on the site and began to talk about the fact that the owner was hiding a deep dark secret, many of the users assumed it had to be pretty bad since the site was after all a teenage dating website. When the owner caught wind of the allegations he promptly banned the user behind the account that began this entire series of following events. He did allow the user of the unknown account a few moments to say goodbye he used those last few moments to type the following words in Japanese though on the main shout box:

"誰かがあなたの家族に悪いことをしている アレクサ様は彼に私達の家族の怒りを感じさせる 誰かがあなたの子供に悪いことをしている アレクサ様がやって来て彼にあなたの復讐を感じさせる アレクサ私はあなたに懇願し、この男にあなたの憎しみが彼が所有しているものすべてを取り、彼が私達といじっていることを後悔させるように感じさせる"

Which loosely translate to a curse summoning a Legend known as Alexa-sama, that curse set off the entire record of events. It was after the username typed out those words that the owner of the site Richard began to experience strange happenings around his home.
One day while he was cooking dinner for himself and his wife the stove eye exploded and lit the older man shirt on fire he quickly threw the shirt down and had to be rushed to the hospital. He spent a few days in the hospital with third degree burns on his torso back and shoulders; on his second night there his wife began running his site in his absence because she knew how much he loved doing things for the teens on his website.
While she was looking over her husbands website a Private Message popped up from a username written in Kanji it said "Did your husband like those burns I gave him?" 
The older woman obviously curious and slightly startled that this user knew about Richard's injury asked "How did you know about that? who is this?"
The kanji username replies "I told you I gave them to him." a soft girlish giggle echoed in the room where the older lady was before the username replied "You may want to go check on your husband." it was at that time the burns on Richard's body in the hospital began to catch on fire once again except this time the flames were black the old mans wails began to echo through the medical facility as the nurses came running in to see he was on fire once more they quickly extinguished the flames while his wife ran into the room asking what happened and who did this to him. 
Richard pointed to a girl standing in the corner she was wearing a black pentagram dress and a cat ear beanie one eye covered by her hair as he shouted "It was her she lit me on fire she's evil!" he rubbed his pain soaked body wincing heavily as the nurse staff looked at the direction he was pointing before replying that no one was there. After they treated the burns fully they put him on suicide watch before sending him to a mental hospital much to his protest as well as his wife's protests.
His wife kept his site active as depression slowly began to sank in for her due to the constant teasing and taunting of the username written in Kanji. She eventually filed for divorce however the site remained active for many more years. On the final day of Richard's life the girl in the pentagram dress and cat ear beanie appeared to him once more as she smiled "Your wife left you." she giggled in a sadistic tone "How does that feel?" he began to cuss loudly at the girl telling her to leave and never return before swinging punches at the mystery girl.
She giggled at him again her expression entirely blank as she told him "I'll leave you alone but you have to do something for me first." the next day Richard was given permission to sign back into his account by the doctor he used that alotted time as he posted a news statement on his site saying that it would be taken down though he never gave a reason other than Alexa-sama had politely convinced him to take it down.

The day after that statement was made Richard was found hanging in his room with his organs laying in a chair next to corpse and the name "Alexa" was carved into his chest by what looked like the claws of a large cat.
Fundatecity went offline on the clear side of the web after that discovery, however I found it had been recreated on the Deep Web but the owner's username had changed from Maximus to "Alexa-sama" spelled out in kanji. 
Please if you see someone uttering that curse on any website please avoid them and find a way to take the website offline as fast as possible maybe the same thing that happened to Richard will bypass you.