From Shoujomagic:
Haruka is a sweet, innocent high school girl who is very excited to meet her new step-brother, Tsukasa. Since her father works overseas, Haruka has been living alone, but now that her father has remarried, she'll have little grade schooler Tsukasa with her while both their parents are out of the country. When they finally meet, Tsukasa is even cuter than Haruka had hoped! He wants to get her help with his homework and sleep in her bed...and undress her and make love to her!?

Story 01) (English Title) The Cupid Who Ran Off; (Japanese Title) 駆けだしたCupid(キューピッド); (Romaji Title) Kakedashita Cupid [Kyuupiddo]:
Mayumi is a shy high school girl who watches Yamano from the other side of the fence after school; she loves the exhilarating moment when he high jumps and is flying through the blue sky. She can see it even when she closes her eyes. But is she so intent on watching Yamano-kun... that she doesn't notice that he's watching her, too?

Story 02) (English Title) I Can Hear the Footsteps; (Japanese Title) 足跡が聴こえる; (Romaji Title) Ashiato ga Kikoeru.: Shizuka's charm bracelet comes with a condition: She can have any wish she wants if she can suppress her favorite thing for two months. Her wish is to be a more grown up woman, but handsome, and surprisingly childish classmate Naoto may make that impossible.

Story 03) (English Title) Peter Pan I Love You; (Japanese Title) ピーターパンのI Love You; (Romaji Title) Piitaa Pan no I love you.: When flighty Eri accidentally injuries Takumi's hand she finds out what a sexist he is. He thinks girls are loud, spoiled, and cry easily. Eri is determined to prove him wrong. Is Takumi a jerk, or could he secretly be a nice guy?

Story 04) (English Title) Of Course I Can't Wait Until Nightfall; (Japanese Title) もちろん夜まで待てない; (Romaji Title) Mochiron Yoru made Matenai.:
Haruka's grades have been falling, and she's pretty sure she knows the reason: Her new stepbrother and affectionate lover Tsukasa. To keep herself from being distracted, Haruka imposes a no kissing rule on Tsukasa. But he's not going to give up without a fight...

A collection of 6 stories.
From Shoujomagic:

[STORY 01]
(English Title) I Don't Love You
--"If you always say 'I love you,' you'll find happiness." Thanks to grandmother's good luck charm, Rio is a very happy and bright high school girl, well-liked by everyone because she tells everyone that she loves them. ...Except for a boy in her class named Kaito. For some reason, he's different from everyone else. He makes Rio nervous and gets her heart pounding, and she can't communicate an "I love you" to him. Just what's going on!?

[STORY 02]
(English Title) Beyond Love

[STORY 03]
(English Title) The Terms of a Kiss

[STORY 04]
(English Title) Touched by Love

[STORY 05]
(English Title) Surprise Attack

[STORY 06]
(Japanese Title) Happy

[From ShoujoMagic]:

Ijiwaru Tenshi Ayumi is a high school student. Her friend's brother, Shouma, is younger than her, but he looks handsome and older! Shouma asks Ayumi for her digits right off the bat, and he's smooth like a player--not really Ayumi's type. The more time she spends with him, though, the more she likes him. But is Shouma really sent from heaven... or is he just a tease?

When Yuuki first meets Akihisa she is less than impressed. Not only is he stalking her, but he also tries to seduce her knowing full well she's a high school student who already has a boyfriend. She can't stand him at all so why is she so drawn to him? On the surface Akihisa seems like the worst kind of man... Is he just toying with Yuuki or does he really care about her?

No one knows that 1st year Rena (16) and upperclassman Kyouta (18) are in fact married. This manga follows them in their lives to discover more about each other and keep the fact they are married a secret from everyone at school. They'll be tested in Jealousy, love confessions, exams, love, mother in laws, embarrassing situations, noisy neighbors and teachers.
(Source: Onigiri-Gakuen)

From SugarManga:
Couple rings...you exchange it with the one you love. What happens when your ring is with the one who loves you, and not the one you love? Mika was rejected by the one she loves when she confessed and her ring ends up with Keigo. What will happen between them and who will she end up with?? The one she loves or the one who loves her?