Total Recommendations: 18
Both series are a casual slice-of-life with a gentle feeling. However! Stories of Those Around Me is not sexual in any way.
Both series are about children being weaponised. Chise gets turned into a weapon, while the children in Bokurano are forced to fight in a giant robot against other robots. Dark themes fill both of these manga series, with characters suffering through hardships alone and together. Both series are also on a very large scale, but Bokurano includes more characters. Friendship and love is also a focus of these comics.
Both series feature a few main characters in a sci-fi impacted world where things get progressively darker and darker and the characters have inner monologues about their suffering. Both about teenagers, high schoolers, and friendship (but no love in Alien 9).
Two slice of life series with a focus on romance. Bonnouji is about a man living in an apartment filled with stuff from his brother. Story of Someone We Know is a series about three Korean women who are friends -- one's been with her boyfriend for years, the second's been with hers for a shorter time and the third is single.
Another Josei love story with the main character being a rich businessman as opposed to an inexperienced medical receptionist.
Both series feature a protagonist drawn into a scary urban legend with little to no knowledge of it or how to deal with it.
Both series feature a protagonist with psychic powers who try to help others using their abilities.
Both series are about a female lead/woman doing detective work/odd jobs for other people. Also contains some random nudity within the series at spots.
Both manga series feature a couple of people trying to survive after a major disaster.
Giant tentacle fights and two beings trying to save the planet. I think Inugami is on a much larger scale.
Both series feature an unwitting student merging with an alien being to save the planet.
Both manga are about kids experiencing something different, and have similar tones in terms of the story and atmosphere.
Both are about dealing with an outbreak of disease in Japan. Manhole has a darker tone to it.
It may not seem similar, but the interactions between both Rei and Kira resemble those between Shuri and Sarasa. Basara's story is much more large scale, with a large variety of characters, which may give less room for character development, but the romance between Shuri and Sarasa plays a big role. Mars' story is very small-scale and focuses on the relationship between Rei and Kira.
They are similar only in that a ghost contacts a human and they develop a relationship over time. The series, however, had completely different tones to them, as Tasogare was dark and depressing, and Ginban was mostly upbeat. Both characters experience hardship, however, Tazusa faces the hardships with her life, and Niiya faces them when trying to live with Yuuko.
Both manga deal with combat against a disease. The differences are that the disease in Emerging has already broken out at the start of the manga, and develops naturally, whereas the disease in Bloody Monday is engineered. Bloody Monday deals with much more government conspiracy than Emerging.
H20 is a lower quality version of Clannad. You have a protagonist who has different circumstances--blindness in H20, and delinquency in Clannad--who is followed around by or meets a harem of girls. Cue crazy back-stories and a plot that just throws in random problems to make it seem spicy and you have either series. The difference is H20: Footprints in the sand finishes in half the time.
I'm recommending one of Junji Ito's series because his works and this series feel incredibly similar. It may not be just Uzumaki, but his Museum of Terror (Tomoe, perhaps) feel really the same. However, Uzumaki had me genuinely frightened without being explicit, whereas it felt like Hikari Club did things just because they could (tie it to the characters if you want).