Psyren, Accel World Recommendations
Both series takes place in another alternate world where strange technology is involved. At the same time, they meet a strange girl who is a beauty while forming a special bond with them.
Both series contain science fiction themes that explores technology beyond our times. There are antagonists that opposes the main characters and their friends but also a little mystery behind the scenes regarding them.
Both series employs action, drama, comedy, some emotions, and later on romance.