From Kotonoha:
Takeda is diagnosed with cancer and feels that he has nothing to live for. His wife also had had cancer, had died of it in fact, and his only daughter has been missing for fourteen years.

One day, when he is about to attempt suicide, the phone rings. It’s the police, and they inform him that the dead body of his long lost daughter has been found, that it appears to have been a homicide. Takeda is crushed but resolves then and there to spend the remaining days of his life hunting down his daughter’s killer.

The time left for Takeda to live equals the time left to put the murderer behind bars. Life is a heart-wrenching story about a father’s willpower and his search for the truth.

Itou Kaiji is a bum who steals car emblems and slashes tires on what seems to be a regular basis. This routine changes one day when he is paid a visit by a man in a trench-coat. Once the two get talking, it seems that the visitor (Calling himself Endou) is a debt collector. The reason for his visit is an unpaid loan which kaiji had previously co-signed for a work-mate (Furuhata Takeshi). The original loan was 30000 yen and once Takeshi had disappeared, the loan then fell on Kaiji.
Kaiji is then told of a way to clear the interest compounded debt (which stood at 3,850,000 yen), which involved getting on a boat with others in his position. Once on the boat the debtors would then have to gamble with loaned money, which would end with a few winning, and others getting into deeper debt and having to work to pay of their debts. After some coercing kaiji accepts a position on the boat, in order to clear himself and make a bit of money as well...
(Source: AniDB)

Ukai Rei saves three troubled teens from a Suicide Website, and together they choose to work as modern-day 'Robin Hoods' of society. However, Rei's friends are caught by an underworld gang whose heist the group had foiled. In order to rescue them, Rei is forced to enter a gambling competition hosted by a rich, rotten old man who is looking for a talented gambler to be his rep player in an upcoming gambling tournament for millionaires from all over the world. The reward money? ONE TRILLION YEN.

Note - This story is directly continued in its sequel.

After awakening from an eight-year-long coma, Kurosawa must face the trials of homelessness.

Takafumi Ten is called to a mahjong club one night to play again Ikawa Hiroyuki, a young mahjong player. Having just robbed Ten's friends blind at mahjong, Ten arrives to take back his winnings.. Ten's mahjong style becomes more apparent as the game progresses...amateurish! Ten cheats in the last round, using a move called the Tsubame Gaeshi, and winning with a Tenhou hand. Hiroyuki is angered once Ten admits he cheated after the game. Will he come to understand Ten's "Way of Tenhou", where Ten willingly cheats and gets beat up in response for his friends? Will Ten unlock his true mahjong potential or cheat forever?

No matter how much time passes, and no matter who they are, the love one has for their parents does not change. A heartbreaking tragedy about the memories a son has of his late father.

Katagiri Yuuji is a divorced, single, lazy gambling addict whose only real activity is playing Pachinko. He does it well enough to get by, but his life is more or less empty... until a young girl named Miura Satomi appears, who is a big fan of his. A classic story by Fukumoto about Pachinko, attraction, and the thrill of gambling.
(Source: MU)

One incredibly tough kid tries to clear his name. He’s no murderer, and he’ll do whatever it takes to prove it…

In the aftermath of the disclosure game that won two Mahjong anomalies, the villainy "17 steps" game. Kazuya sets forth a gamble of 1,200,000,000! How will Kaiji survive?!

A direct sequel to Tobaku Datenroku Kaiji, picking up immediately after Part 3 ends. After his tremendous victory in 2-Player Mahjong against the villainous President, Muraoka Takashi, Kaiji is being driven home by Kazuya, the son of Chairman Hyoudou. However, in the car, Kazuya asks Kaiji if he would be interested in one more gamble that night, and Kaiji accepts. What surprises lie in store for our dear Kaiji, and what will the gamble be?!

Morita Tetsuo's life changes when he meets Hirai Ginji, who works in the unknown and mysterious 'back world' of society full of villains.

A collection of short mahjong-centric stories by Fukumoto Nobuyuki.

Itou Kaiji, now free of debt but without a penny is leeching himself in Mr.Sakazaki's new house, despite all the flirtings (extreme torment for Kaiji) from Sakazaki's daughter, Mikoko. Sakazaki attempts to kick Kaiji out, even by offering a farewell 'we never knew each other' money of 3000000 yen. While Kaiji ponders himself on the decision, he is visited by Miyoshi and Maeda, two of his 'allies' he had saved from the last part of the series.

This is part 2 of Gambling Emperor Legend Zero, picking up a few years after the cliffhanger ending of part 1.

Japan, 1995. After graduating from high school, Itō Kaiji moves to Tokyo to get a job, but he fails to find steady employment because the country is mired in its first recession since World War II. Depressed, he festers in his apartment, biding the time with cheap pranks, gambles, liquor and cigarettes. Kaiji is always thinking about money and his perpetual poverty frequently brings him to tears.

Kaiji's unrelenting misery continues for two years until he is paid an unexpected visit from a man named Endō, who wants to collect an outstanding debt owed to him in Kaiji's name. Endō gives Kaiji two options - either spend ten years to repay this outstanding debt, or board the gambling ship Espoir ("hope" in French) for one night to clear the debt. Using a con, Endō pressures Kaiji into accepting the deal, believing he will never come back from the voyage.
--Wikipedia

The manga is divided into three parts:
Part 1: Volume 1-13 (Complete)
Part 2: Volume 14-26 (Complete)
Part 3: Volume 27-39 (Complete)
Part 4: Volume 40-? (Ongoing)

44 years old, single, working in a construction company for his entire life. All Kurosawa wants is a little respect from his co-workers. And a little popularity won't hurt. Unfortunately Kurosawa's plans fail miserably from time to time and one day, he finds himself right in the middle of a fight against...delinquent middle schoolers?

The continuation of the Kaiji series, picking up immediately after the end of One Poker Hen.

Spoiler (mouse over to view)One Poker has been concluded, with Kaiji emerging as the victor and claiming the 2.4 Billion Yen as a prize! But now, a new problem arises... how can the Asian Trio take it with them with Kazuya's Black Suits gathered right outside the entrance of the warehouse?!

The 6th part of the Kaiji series.

1. Tobaku Mokushiroku Kaiji

2. Tobaku Hakairoku Kaiji

3. Tobaku Datenroku Kaiji

4. Tobaku Datenroku Kaiji - Kazuya Hen

5. Tobaku Datenroku Kaiji - One Poker Hen

6. Tobaku Datenroku Kaiji - 24oku Dasshutsu Hen

Watanabe Yuuichi, also known as Pen-chan, loves mahjong. It's just too bad that he's not very good at it. Follow Pen-chan's wins and losses (mostly losses) in a series of short tales about his friends, family, co-workers, and local yakuza until the final conclusion where Pen-chan makes the biggest gamble of his life...