Lonely Castle in the Mirror - Recommendations

Alt title: Kagami no Kojou

If you're looking for manga similar to Lonely Castle in the Mirror, you might like these titles.

Karate Survivor in Another World

Karate Survivor in Another World

When 34-year-old Nozaki Hitoshi is hit by a truck, he is sent to a fantasy world by a dismissive god and dropped into a harsh wilderness without even the clothes on his back. His only salvation is a newly granted karate skill and his general survival instincts. Luckily, Hitoshi is up for the challenge–he’ll weave clothes out of tree bark, test fruit for poison, and crawl through the mud to test his kicks and punches against goblins and other creatures. No matter how much he levels up in this world, he still longs to find other humans to share his solitude. An engrossing fantasy that pits karate technique against swords and sorcery in another world!

The Chronicles of Narnia: The Magician's Nephew

The Chronicles of Narnia: The Magician's Nephew

On a daring quest to save a life, two friends are hurled into another world, where an evil sorceress seeks to enslave them. But then the lion Aslan's song weaves itself into the fabric of a new land, a land that will be known as Narnia. And in Narnia, all things are possible.

The Chronicles of Narnia: The Lion, the Witch and the Wardrobe

The Chronicles of Narnia: The Lion, the Witch and the Wardrobe

Four adventurous siblings—Peter, Susan, Edmund, and Lucy Pevensie—step through a wardrobe door and into the land of Narnia, a land frozen in eternal winter and enslaved by the power of the White Witch. But when almost all hope is lost, the return of the Great Lion, Aslan, signals a great change... and a great sacrifice.

The Wolf Never Sleeps

The Wolf Never Sleeps

Seeking strength and glory, the adventurer Lecan challenges monster and maze alike. Until one day, he finds a mysterious black hole…leading to another world! The only question is—can he survive the new world?

Isekai no Meitantei

Isekai no Meitantei

A story about a dull detective mystery fanatic who, upon dying, gets reincarnated into a different world.

Route 225

Route 225

One day, Eriko finds her little brother Daigo on a swing set, too embarrassed about getting bullied to go home. After cheering him up, the pair heads back to their house… and ends up at the ocean, despite the fact that their hometown is nowhere near the sea. This is strange enough on it’s own, but when the siblings encounter an old classmate that they are certain died a few years ago, they realize they have stumbled into a parallel world. Desperate to return home, but with no knowledge of how, the siblings try everything in their power to return to their happy life.

Sono Saikyou, Kami no Irai de Isekai e (Light Novel)

Sono Saikyou, Kami no Irai de Isekai e (Light Novel)

World of Immortals (Novel)

World of Immortals (Novel)

The World of Immortals, it is the world every mortals long for. For many, it is an eternal glory to distort the dimension and enter the World of Immortals. But the vicissitude of time is simply merciless, the legends regarding immortality had long been forgotten. However, a miracle shall rise once more! An immortal was about to distort the dimension with martial arts and cut all ties with the mortal world. The protagonist, Xiao Chen, was caught up in it and accidentally brought to the World of Immortals. What will they find in the vast world beyond the rift?

Thousands of Dreamless Years

Thousands of Dreamless Years

Lan Xieyi, an ordinary boy, wakes up one day to find he's travelled through dimensions and has become a demon's male pet! And he's even being used by the owner of this body to act as Bai Yueguang's substitute - this demon slave's body is actually quite sweet! He must deal with the owner of the body, the Dragon Prince, Di Jiang; the cold heavenly immortal, Liu Yun; the wolf in sheep's clothing, You Chang; and the beautiful phoenix Bi Wu. Their love makes Xieyi hesitate - if this is a dream, then when will he wake up? Where does this nostalgia in his heart come from? After transmigrating to a new world, the male pet strikes back and creates his own harem of beautiful men!

No Fatigue: 24 Jikan Tatakaeru Otoko no Tenseitan (Light Novel)

No Fatigue: 24 Jikan Tatakaeru Otoko no Tenseitan (Light Novel)

Coming out from a Game Center, the protagonist comes across a random slasher, gets into a scuffle with him to try save a female high-school student and stabs the slasher who dies. The protagonist is then mistaken as a criminal by a policeman coming at a bad time and is shot to death, ending his 30 year old life….. or so it should have been. However, a goddess of another world sympathised with this protagonist too much and let him reincarnate in the other world. The condition was to defeat the slasher who tried to reincarnate into the same world.Thus the protagonist had [No Fatigue] ― he reincarnated into the other world with only the skill of not tiring mentally or physically.