D.Gray-man

• Chapter 1: 旅たちの聖職者(クラーヂマン) / The Travelling Clergyman
Allen is en route to the Black Order's HQ and has arrived in England where he was born. He catches up with Mother, an old nun whom he and Cross stayed with after Mana died. Allen is asked to talk to a nurse who'd recently lost her lover. 

• Chapter 2: 魔女の棲む村 / The Village where the Witch Dwells
Centers around Kanda Yuu

• Chapter 3: バク．チャン狂想曲(カプリッチオ) / Bak Chan's Rhapsody (Capriccio)
Centers around Bak Chan

• Chapter 4: 1000の悲劇 / 1,000 Tragedies
Centers around The Millenium Earl

• Chapter 5: 四十九番目の名前 / The 49th Name
Centers around Lavi and Doug

• Chapter 6: 黒の教団親睦パーティー / Black Order's Reunion Party
Centers around the Black Order

D.Gray-man(Zone) is a one shot manga that is considered the pilot or  starting point of D.Gray-Man. It is also known as chapter "0" of D.Gray-man and shares many similarities to the story.

About a boy of thirteen years who always tries to be a hero and for various reasons are involved with monsters, ending in his death, but it revived with the help a little thing (one might say that is the predecessor of innocence) and now must fight the Count ancient.