Arasaa Majutsushi no Yuru ii Harem Life ~Black Shachiku ga Isekai de Jiyuu Kimama ni Yuukyuu Shouka~

This is the story of a nearly-30-year-old office worker who suddenly remembers—he was a powerful mage in a past life! Now, he switches back and forth between the two worlds, living a laid-back, slow-life existence. But one day, out of the blue, he's approached by a fierce female adventurer—from the legendary all-women Valkyrie party, rumored to hate men! Just what will happen to this near-30s mage's peaceful, dual-world life now!?