You've Got Mail: A Cautionary Tale - Chapter 68 - Is This In The Hands of Fate or Mine?

Nine Realms Sword Emperor, a legend returns, leveling everything.Genius monsters, trampled underfoot, powerful beings, wiped out with a wave of a hand.If people do not offend me, I will not offend them; if people do offend me, annihilate their entire family.

Yukima Azuma—charismatic, confident, and utterly unforgettable. He was the man every girl wanted but could never truly keep. One by one, they fell for him, only to be left with memories they couldn’t erase.Kasumigaoka Utaha: “I was his first, the one who taught him love… only for him to use it on other women.”Sawamura Eriri: “If I hadn’t been such a tsundere, maybe things would have been different.”Yukinoshita Yukino: “He was my light in the darkness, the only one who ever truly saw me.”Yukinoshita Haruno: “That bastard ran away after taking everything from me.”Hoshino Ai: “My only true love. The one I can never replace.”And when asked about their relationship with him?“Ex-girlfriend.”But to the women still in his life?Sora Ginko, Kato Megumi, Sagiri, Bocchi, Shinomiya Kaguya, Kirisu Mafuyu, Suou Yuki, Alya—“Thieving cats.”Because no matter how much time passed, no matter how far he went—one truth remained: Yukima Azuma was the one man they could never forget.

The 7-year-old little crybaby met 11-year-old big brother who ran away from home.
[This man became the protector of redemption in his life]

The 16-year-old little dragon fell in love with a 20-year-old big brother.
[It’s a pity that the big brother didn’t recognize him as the little crybaby]

The 23-year-old single father and 27-year-old chief executive meets again.
[This time the little crybaby and his big brother are finally together]

Fortunately we met through hundreds of millions of people, Thank God, for letting us break through many obstacles and get back together again, falling in love with you and being with you again is the greatest fortune in my life.

- Description from Novelupdates

Cassian Ven Dyke, the bastard son of a powerful ducal family, grew up in the slums of Veldora under the care of his father figure, sword master Russel. When Russel passed away, Cassian was left with only a silver necklace as his inheritance. After putting it on, Cassian was attacked by three psychotic thugs who tortured him in an attempt to steal the necklace. Refusing to give in, Cassian was ultimately stabbed through the heart with the very same necklace. Instead of dying, he mysteriously vanished as the necklace lodged itself in his heart. Just before disappearing, he heard an eerie message echo in his mind:[True mana detected. Origin: Human...][Human detected. Compatibility with system: Confirmed.]