Duke Tougou - otherwise known as Golgo 13; he's loved by the ladies, hated by his enemies, is enamored with firepower, and can take out a target from several kilometers away. With an arsenal of weapons at his command, Golgo 13 is hired by a variety of people to take down hijackers and more - but he also must protect himself against those who want to take down the legend himself!
Henrietta is a young girl who works for a "welfare group" that does the government's dirty work. Cybernetically-enhanced and specially-trained, she is one of a group of elite hit-girls, remorseless killers with no memories of their past. Jose, her partner, has taken care of her since she was brought into the organization following the murder of her family, and struggles between his affection for her, and his opposing duty to his employer. But, time is running out.. for with each bullet they fire, Henrietta and the other girls lose a little more of their humanity.
Professional assasins! Both shows are not about Ninjas, but rather modern-day, gun-armed killers. There's a curious simularity between the principal characters, too: they do not feel the slightest remorse for what they do. This is because the Gunslinger Girls have been brainwashed, and because Golgo 13 has a completely inscrutable personality--we never learn his motivations. In both cases, killing people is just a job, nothing personal, you might say. Also, both shows delve into the dark underside of society--crime, corruption, etc. There are no "good guys" in these shows, which is an original and intriguing dramatic technique in itself.
Mireille Bouqet has become a reputable assassin working in France. However, all changes after she meets Kirika, a mysterious young girl who knows nothing about her past but possesses killing skills that dwarf hers. Further intrigue unfolds as both characters explore their shadowy past and come to a head with a clandestine organization that seeks to control destiny itself.
Beppu Yugo is one of the world's most successful and celebrated negotiators. His cases have ranged from big to small, from secretive to in the public eye. His work doesn't come cheap, but his skills are the top of the line, and through words, not violence, his failure rate is minimal. After a period of inactivity, Yugo is back on the job, to help negotiate the release of a hostage in Pakistan. With harsh terrain and deadly enemies before him, will he survive long enough to save the hostage, and return with his life?
While Yugo is more political and Golgo is more of a James Bond-style manly men anime, I still think this is a decent recommendation. Golgo 13 could be renamed as "stand around and do nothing and talk about guns," and Yugo has similar moments (albeit involving politics or other things, usually).