Seinen anime and manga are aimed at an older male audience and typically feature more mature themes, complex storylines, and psychological elements. Here are some popular seinen recommendations:

Kaito left the shop that day with a newfound appreciation for the power of storytelling and a sense of wonder that he would carry with him for the rest of his life.

Unlike the "power of friendship" tropes in most sports series, Blue Lock is about egoism. It’s a high-stakes battle royale where 300 strikers compete to become the best in Japan. How to Choose Your Next Series

One day, a young adventurer named Kaito stumbled upon Netori's Nook while exploring the city. As he browsed the shelves, he discovered a peculiar, ancient-looking tome bound in a strange, glowing material.

I'll narrow it down to one perfect series for you.