Naruto: The Outsider's Resolve - Chapter 1.4 (014):

She thought heartbreak was the hardest battle she'd ever fight. Ending a five-year relationship in 2024 nearly broke her, but she rose anyway. By 2028, she’s everything she once dreamed of becoming. A bestselling author, an admired high school teacher, and a successful businesswoman. But behind her perfect image lies a dangerous secret. She’s also one of the most feared underground hackers in the cyber realm.Then one night in City X changes everything. A book signing. Too many drinks. A stranger with a voice like sin and eyes full of danger. The next morning, no memories, a blurred signature, a hotel room, and a man’s touch she can’t forget. Back in City C, she tells herself to move on. Until someone knocks on her door. And the man from her forgotten night says the words that turn her world upside down.“I’m your husband.”He’s younger, commanding, and far from ordinary. A soldier from a secret military unit hidden in the shadows, where forbidden experiments and enhanced beings redefine humanity itself. Now bound by a contract marriage, they’re forced into a world of covert missions, coded lies, and a war between love and survival.She’s a hacker who steals secrets.He’s a soldier sworn to protect them.And when their worlds collide, love becomes both a weapon and a weakness, the only thing powerful enough to save them... or destroy everything they stand for.

Huang Dan’s pain nerve is innately different from the ordinary people. A little tore in his skin can cause him to sweat all over his body painfully to the point of him unable to make a word out.

Somehow, he began to cross world, following Mr. System to do the tasks…

In the first world, Huang Dan realizes what it means to die painfully and to live to die again.

TL’s summary:
MC suddenly transmigrated and is bind to a system, requiring him to solve mysteries. Born with a higher degree of pain sensitivity, he met different people in the different worlds and learns what kind of emotion smiling is.

- Description from Novelupdates

In the book, the supporting male lead is the older brother of the female lead. The supporting lead has a cold and desolate personality and is despised by the female lead due to his terminal illness. However, when the female lead acted viciously and was abandoned by everyone, he still protected her, sacrificing everything for her and even dying for her.Su Ci has transmigrated into the book, becoming a little rabbit raised by the supporting male lead, and she has discovered that her life is tied together with this terminally ill supporting male lead.After becoming a little rabbit, Su Ci can only sleep on the supporting male lead’s dusty bed every day, eat withered carrots, and guard against the female lead, who occasionally tries to pluck her rabbit fur. To turn back into a human, she needs to find ways to get close to him every day.The supporting male lead noticed that lately, his pet rabbit always wanted to kiss him. Until one night, he leaned down and kissed this soft little creature, and it unexpectedly transformed into a beautiful little fairy!…The female lead encountered trouble, so she went to look for the supporting male lead, whom she always looked down upon. Unexpectedly, the young man, who was previously poor, down on his luck, and nearing death, had become a scion of a wealthy family in a blink of an eye, and by his side was a girl as beautiful as a fairy.But what made her jealous was that the always-cold and aloof supporting male lead actually kissed that girl gently in front of everyone!

When The Cute Kunoichis Spied on Their Teacher's Secret is a light novel written by Kazuma Kamachi and illustrated by Ryuushi Tajima.

The story takes place in a world where Japan never ended their isolationist phase, and agents from foreign powers are always threatening to steal the country's advanced technology. In order to combat this threat there has been a resurgence of ninjas that use Strategic Martial Arts, techniques that combine cutting-edge modern technology with a traditional foundation of martial arts and ninjutsu. The story follows Souha Sugiyado, a 17-year old ninja instructor and former ninja prodigy who was forced to retire from active duty by the wounds he suffered in his last mission. Souha's four students are all kunoichi who have all gained the rank of Elite Ninja, the highest official rank available to ninja. However, one day two Shogunate ninja approach him with the news that his four students have gone rogue and have stolen a portable modular nuclear reactor, and thus they ask for his help in bringing his students to justice.