Isekai’d as a side character

In the reborn world, the Crown Princess is voted for. I'm a very normal extra, so it's nothing to do with me. But why did I become a candidate for the Crown Princess?
• ⍰

Regaining the memories of his past life, Cyril realizes that he was a character in an otoge and valet to the villainous Sophia. At the rate things are going, Sophia will have the prince stolen away from her by the heroine, fall into darkness, and be executed. Wanting to save the young lady he is so fond of, Cyril moves to eliminate all the factors that cause her to fall into darkness.
• ㊉

The main character is reborn as a character from a game he played in his previous life. This character falls into ruin along with the villainess, spending the last of their years together. A man named Kururi Helan.
• ③Ⓧ

Oh Mari is reincarnated into the novel “My Dorothea” as the heroine's best friend, Maristella. Aware that the heroine, Dorothea, ends up betraying Maristella, leading to the execution of the latter, she vows to do her utmost to survive and live her new life to the fullest.
• ⍰ ◉

I spent a carefree day lounging about after paying off my tuition loans, but ended waking up inside a novel as the Amel, the only daughter of a poor count. Even if I worked for the rest of my life, the debt my family accumulated is too much for me to even be able to pay off. Not only that, but it seems that I ended up having a one-night experience with Kyle, the male lead, after getting stupid drunk...
• ㊉Ⓧ
• TW: sex w/ one party drunk

“It’s just like Murim.”
As I hurry to perform first aid in an attempt to save even one person, I realize that this world is that of “The Supreme Demon King,” a Wuxia novel I’ve enjoyed reading.
• ㊉
• If confused by description here, see Wikipedia articles “Wuxia” and “Wulin”

Wishing for a new life, Asili Rosé was reborn as a princess in a novel she once read. She thought she was born with a golden spoon, but it was actually just a gilded spoon?
Once she realized that nothing but ruin awaited, she found a diary foreshadowing the future...
• ⍰ ◉
• TW: suicide; torture; PTSD

A guy finds himself transported into the world of a classic horror movie. And what’s more, as the “slutty character” who dies first!
• ③◉♡
• Not your traditional transported-into-a-work-of-fiction isekai, but it counts!

Somehow, before the appearance of the female lead, I became the male lead’s wife. Since things had already turned out this way, I decided to try my very best. But what will I do when the heroine inevitably comes?
• ②
• Though referred to as a villainess, the original Dylan was just a very sleazy side character
• TW: stillbirth (mentioned); maternal death (mentioned)

My favorite secondary male lead, Kaelus, died. Living in poverty without him, I eventually became ill and died as well. I thought I would return to reality, but I went back in time instead.
This means I have to save my beloved, right?
• ㊉