Devastating last page/s (short, mostly BL)

Oneshot Pg.185-209
First half it's just like a surprised story of a scaredy-cat crybaby brother. Second half reveals that actually he had an unrequited incest love though he's already moved on.
Bitter ending

A rich, successful, handsome man finds himself looking for something new in his life. Taking advice from his past lover, he seeks a roommate, an "easy relationship". However, a male mistakenly shows up at his door instead of a woman.
Tragedy (in a mind-blowing way)

NOT a oneshot (12 chapters) but it's a quick and incredibly absorbing read. So no need to procrastinate on it. If there's something you don't understand, just ask me!

Story ch.2-3
A high school student is submitting to sex with a yakuza in order to repay his father's debts. The father was keeping drugs for the yakuza but ended up using them and became addicted. The only bright light in the student's life is his lover, but one day he makes a horrible discovery.
Tragedy
Tearjerker

Oneshot ch.1
Depicts an innocent student being possessed by the demon he mistakenly freed from a mirror, and is left with the heavy consequences for its actions.
Open, bitter ending
Tight throat

Oneshot ch.11
Ryoya has finally returned to the house he has spent the last 20 years avoiding, gathering at last the courage to read his friend's love letter.
Tragedy
Tearjerker

Oneshot ch.7
Yuu was in love with Asaya went they went to school but he never confessed. They meet again after 10-12 years but it is too late for them to be together.
No happy ending

The devotion and life-long unrequited love of the man who yearned to one day replace his mentally broken friend's first love - and its tragic denouement.
Stays unrequited, Tragedy

Oneshot vol.1 p.134-143
His partner's phone's incessant ringing - surely from another lover - no matter the time of day or night, is driving him over the edge with worries & insecurity...
Tragic ending (not a tragedy)

Sold by his parents to a brothel, Yuki is placed under the care of the mysterious Shirogane. They are in love, but they can't be together because of regulations. However, a tragic turn of events will allow them to finally be reunited - with a deadline.
Tragedy
Tearjerker

Pairing: Levi & Eren
After their victory against the Titans, Eren falls victim to a degenerative sickness.
Tragedy
Tearjerker

I didn't expect it to so much... but it did.