Shamisen is a traditional Japanese musical instrument that looks similar to a guitar. Teenager Sawamura Setsu’s grandfather who raised him and his older brother Wakana, recently passed away. His grandfather was one of the greatest Shamisen players and the two siblings grew up listening to him play and learning to play the instrument.
Since the grandfather’s death, Setsu dropped out of high school, moved to Tokyo and has been drifting, not knowing what to do besides play his Shamisen. That’s when his successful and rich mother, Umeko storms into his life and tries to shape Setsu up. She enrolls him back into high school but little does Setsu know that he is about to rediscover his passion for Shamisen.
(Source: BakaUpdates).

Takuya is a normal Japanese elementary student whose mother died not very long ago, leaving him alone with his father and his baby brother Minoru. But his father is a busy man, and Takuya has to look after Minoru. Because of this responsibility that would normally never burden a child of his age, Takuya sometimes resents his fate and his baby brother... but his love for Minoru gives him the strength to carry on.
(Source: ANN) Included one-shots:
Volume 2: Time Limit
Volume 4: Secret Boy ni Tee Dasuna!!
Volume 6: Baka de Karukete Wagamama de
Volume 15: Natsu to Kimi no Irradiation

Ide Nobuhisa has always been a boy full of vitality and a young promise in the field of track running. However one day after a competition, he stumbled over the pretiest pair of legs he had ever seen! Their owner, a young girl practicing tennis makes a promise with Ide that she will teach him how to play. After seeing the name tag on her racket bag, Ide puts all his efforts into passing the test for accessing the same high school she goes to, Makunogama. In his first days in his new high school, Ide discovers two things: an old friend of his is also attending, and nobody knows of a girl with the name he saw on the tag! He and his friend join the school tennis club, where they meet another first year, Takita Louis (Ruui), a very good tennis player with a little of an attitude problem.
However things start to look better for Ide when his dear missing girl appears in the school! As it happens, he misread her name on the tag. Takada Hinako was well known as one of the members of the tennis club, but some time after meeting Ide for the first time she suffered an accident and has now lost the use of her left leg. Hinako is no longer a happy spirited girl and tells Ide she can't fullfill her promise.
Eventually the opposite characters of Louis and Ide end up confronting each other in a tennis match. Ide is an incredible fast learner, but he is no match... until Hinako decides to give him advice. Things only get worse, however, when their club president decides to put Louis and Ide as a doubles pair for the upcoming inter-highschool tournament! (Source: M-U)

From "Manga: Sixty Years of Japanese Comics" by Paul Gravett:

It follows the lifelong relationship between Kain Walker, a New York cop who has hidden his homosexuality, and his younger blond boyfriend, Mel Frederics, an orphan with a troubled past.