If you're looking for manga similar to For Whom The Alchemist Exists, you might like these titles.
The vast universe that spreads endlessly... There are as many hopes and dreams of people as there are countless numbers of stars...as well as nightmares... During a planet investigation, Claude came in contact with a strange energy field and got transported to an unknown planet. There, the earth swayed and monsters terrified the denizens. Claude met a young girl named Rena, and in addition to searching for a way to return to his world, he went on a journey to investigate the calamities that had been troubling this world.
Twelve heroes thwarted the Ten Wise Men's plot to destroy the universe. Four hundred years have since passed. The date is SD 772. The Pangalactic Federation has already explored one third of the Milky Way, and continues to research in its insatiable quest for even more power. In that time, the young Earthling Fayt Leingod and his family visit Hyda, a resort planet in the Pangalactic Federation when, suddenly, an unknown military space force attacks Hyda. The assault leaves buildings destroyed and the resort's natural surroundings in ruin. Amidst the chaos, Fayt attempts to escape with Sophia and the other resort guests to an emergency shelter, joining his parents along the way. But even their escape route falls under attack. Fayt manages to reach the shelter, but he is separated from his parents...
Noah is a youth that is the final survivor of Earth, sent out by his scientist mother in a spaceship to find a new world. He then encounters a planet where all living creatures have "magic." As he searches this new world, he meets a girl who calls herself, "the daughter of the Demon Lord?!" This is an isekai SF fantasy where a young cyborg travels to a mystery-filled world!
Rena is a girl living in Expel. From a young age, she has always believed strongly in the legend of the Warrior of Light and believed that one day he will appear before her. Then on one day, the Sorcery Globe fell upon the planet of Expel, causing chaos to the planet. Later Rena met Claude when she was at the Shingo Forest, who had saved her from a monster with a weapon that shoots a dazzling light .Rena had believed that Claude was the Warrior of Light in the legend, but Claude had denied it. Despite that, the both of them set off together towards Eluria, where the Sorcery Globe fell, in order to investigate it, meeting new people and gaining new allies on the way.
In cyberspace the battle between magicians unfold. "Fate" might not be "Fate", and now, the new Holy Grail War has begun!
The distant future: In a universe where humanity's mortal enemy is the alien race known as Bugs, an Imperial battleship suffers a mysterious and devastating attack that sends Captain Alan Corinth crash landing onto an unknown planet. Much to his surprise, rather than the technologically advanced humanity he knows, the humans he encounters there seem to live in a fantasy world filled with swords and magic!
In a zombie apocalypse, he looks for a perfect death in the arms of a beautiful zombie girl...
In Academy City, there is a popular next-generation contest. In reality, this is a hand-to-hand battle between gigantic Virtuaroids that appear on the streets. It’s formally called as “Computerized War Machine Virtual-On”. Since it can be argued that Level 5s and Level 0s are equal given the technique, it has spread with explosive force among the students of Academy City. One day, Index with her white Bal Bados, fights Touma’s stock Temjin. “I’m Ririn. Purajina Ririn. I’m not Ririna… Munya…” A seemingly insomniac girl arrives at Academy City. And, Kamijou has an encounter. The usual Virtual-On meets an unavoidable unprecedented accident. That is, the Computerized War Machines fuse with Academy City, a sign of a grand battle about to happen! Misaka Mikoto and her Raiden, Shokuhou Misaki and her Angelan, as well as many others will make appearances!