From Bliss:

Motoki was originally an ordinary guy with an ordinary life. Soon, however, Motoki starts noticing that things are changing in himself and his surroundings. His bad eyesight is cured, and suddenly he becomes prettier. As if in response to this mysterious change, two strange men appear in class, Shidou and Kubota. His classmates tell him that they have always been there, but he has no recollection of them. Then he finds out that both of them are after his life, and planning on "devouring his heart."

1-2. Rival ni Ki wo Tsukero
3. Koishitatte Ii janai
4. Suki Suki

Taku and Mutsuki are friends who no longer talk as much as they used to when Mutsuki gave Taku a brush off. A year later when their parents go on vacation and Mutsuki is left to look after Taku, Mutsuki slips Taku a few mysterious pills that put Taku in a compromising mood.

Warning: This story contains shota themes. It involves older men dating middle school boys.

[from Fantasy Shrine:]
1-4)Being the willful, extravagant 3rd prince, Philnaldo frequently graces the cover of tabloids with his scandalous affairs with women. This annoys his personal attendant, Ralph, to no end! Then Philnaldo propositioned him unexpectedly; in exchange for dropping all his women, Ralph would take their place… in his bed! A royal love story of a prince and his servant, where both refuse to face the true feelings of their hearts… but what happens when a crisis occurs!?

5) The Garden in the Past- Ichika is in elementary school when his father dies. His mother takes him to live with Yuu, a mysterious young man who has a connection to Ichika's father. As his mother becomes more unstable, Ichika grows more dependent on Yuu...

6)Darling 2002- Nishihara is odd-ball president of the puppet club, (yes, that's right, puppet club) and desperate to keep it from being shut down. What he needs is a new member but grabbing the person next to you isn't a good idea when you're standing by Moriya Koyo, the scariest guy in school. Moriya tells Nishihara off, but entranced by his beautiful voice, Nishihara becomes determined to win Moriya over to the puppet club! Stalking, badgering, and chasing, nothing is off limits for Nishihara.

Preview: Izaki was always confident in school who had to work at being the best. It's very much a you get what you put in scenario. He's more than capable of rising to the task whether it's club or tennis. He also enjoys being contrary to others and seeing through their bullshit and bluster which is so refreshing. He doesn't even do it to show off, just because people's shallowness annoy him.
Hakamada is the quiet one. Still waters run deep asiding from the fact he always seems to look vapid. He's the prodigy in so much as things just come easily to him. He doesn't have to work or study and just manages to come out on top which is frustrating for Izaki who realizes he'll never reach that level no matter how hard he tries.
So there's a bit of a rivalry between them but not so much because Izaki knows he's got no chance of catching up. Although, he doesn't realize that Hakamada was never competing with him. And then there's Hakamada's attraction which Izaki can't understand at all. I love the split between the characters perceptions and their actual motivations. It's really well done.
And it's humorous and there's obligatory smex which is actually quite pretty. So you should read~~ if only for the fact that it's small and won't take up much of your time~

Tempted by the beautiful afternoon, piano teacher, Toshiyuki, decided to play the piano with the window open. Before he realized it, an intruder had barged in through his window!? The intruder was none other than the talented surgeon, Mashiba, who works at the University Hospital nearby. Despite his cool demeanor, this surgeon started to pursue Toshiyuki most relentlessly! “You’re even more beautiful than the music you play,” he professed to the stunned Toshiyuki. Feeling totally harassed, would Toshiyuki be able to get rid of his stalker!?
(source : B-U)

Shirasawa, who sought a lover he could be dependant on, always dated married men old enough to be his father. At such a time, appears Nakatani, a student at the cram school he used to work part-time for. Nakatani passionately tells Shirasawa of his love for him, but Shirasawa doesn't seem interested in having a relationship with younger guys...
(from B-U)

Story 1: Lover's Name
From Ultimate Manga Guide:

One night, Ei Ariga runs into a very obnoxious playboy stranger. Then he finds out that the guy looks exactly like but otherwise is totally opposite to the timid and very polite Ryouichirou-san who lives alone in a very big apt and has hired his services (Ei-kun's father is a private detective), to find out why he doesn't remember doing some things and being at certain places. Ei-kun discovers that the nasty, violent and annoying carbon copy is called Naruaki and things get extremely complicated when he starts falling in love with both Ryouichirou and Naruaki...
Lover's Name was re-printed in Double Lover (2005) with oneshot Kimochi no Yukue.

Story 2: Saikou no Kimi was re-printed in Saikou no Kimi (2007) with two other short stories.

Sonoda Kaiya is a really famous model who's still in high schoool. Tateyama has been in love with Kaiya for a long time. Kaiya only sees Tateyama as a plaything. As for Tateyama, he is willing to do whatever Kaiya wants up until now....

One day Hatsuki was hurt on campus and was helped by Watakabe Tatsuyuki, the most famous idol in school. Hatsuki, being homo, secretly fell in love with Watakabe. However, Watakabe doesn't have any interest in Hatsuki until one day when Hatsuki found out the truth about Watakabe's words: "I killed my little brother".
(Source: Manga Updates)

Katsuse Rin, a troublesome student that's always breaking the rules ends up falling in love with a member of the school discipline squad, Kuramare Fukaten. They run into some problems when Katsuse wants to be more open about their relationship, but Kuramare does not want his school life to be affected by his private life. Will Katsuse and Kuramare be able to overcome this and be the happy hugging, kissing, dating couple that Katsuse wants, or will Kuramare be afraid to let himself be caught by the students that look up to him, forcing Katsuse to move on with someone else?
(from B-U)

Is the astronomy club actually a black hole of love?! Haruki has drifted into the club, but the senpais there are all weirdos... (Source: B-U)

All begins when Soga Naoaki went to complain to the president of the student counsil, Yoshizumi Sekai, about the reducing of his volleyball team's bookings. By coincidence, Naoaki becomes the vice-president of the student counsil because of the health of the current one. He and Sekai don't get along, but what happens when they have to organise the school festival?

It's been three years since Kirima walked away from his relationship with Kou. Kou's obsessive love was what sent Kirima running in the first place, and now that he has Kirima back he's not about to let him escape again...

Morio is fascinated by his new high school teacher Saeki-sensei. Despite Saeki-sensei unsociable, cold and unfeeling attitude, Morio finds himself following his every move. But does Morio simply admire his new teacher, or does he desire something more…

From DMP