MTL - The Portal of Wonderland - v2 Chapter 22 Mystery man

The path of a demon lord is not one to tread lightly when the very world you turn against you. Very few could walk this road without losing their way.On Ryuji’s first day, he and his class get summoned to another world. The moment he arrives the entire class is given power from the goddess of light, Lumina.However, the calamity star appears affixed to Ryuji, and he faces a dangerous and unknown future. The red star's existence warned of the rise of a demon king and the coming chaos to the world.In order to survive and fight against this fate, he gained the class [Berserker] a tool for him to survive in this world.Despite a warm welcome, the obvious happens, and the king asks them to aid them against their enemy, the current Demon Queen. However, the kingdom is keeping something secret from the heroes.With a beautiful fox maid, Ryuji lives his life without constraints. If he wants to help, he helps. If not, he won’t. Armed with a colossal axe, Ryuji revels in the thrill of battle, relishing the opportunity to crush his enemies, regardless of their size!“Tell me. Why do you attack the demons without reason if you desire peace?”

After struggling in the apocalypse for ten years, Yao Ran died and returned to the three months before everything began. She returns with hatred and thirsts for revenge, intent on making those who owe her pay with their lives.With her grandfather's inheritance, Yao Ran sold everything and frantically hoarded weapons, medicine, food, and supplies. She sharpened her sword, stockpiled up supplies, settled scores with scoundrels and villains, and repaid them with both enmity and kindness.When disaster strikes, she begins her revenge, facing a dangerous world, and is determined to outlast her previous life.

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

- Description from novelupdates

The second prince has come of age. To celebrate the advent of such an occasion, the search for a suitable bride began. My younger sister was expected to go to the Royal Palace as a candidate. However, despite this, she eloped the day before her departure. I, the older sister she left behind, looked almost exactly like her – so much that we were often mistaken for twins…

One month, right? For just one month, shall I substitute in for my sister?