Houmonsha

As winter draws to a close, German boarding school student Thomas Werner dies one morning. He leaves behind a single letter addressed to his fellow student Juli that reads "Here is my love. Here is the sound of my heart."

With his faith shaken to the core by the words, the scholarly Juli sinks to the depths of despair. His cynical roommate Oscar finds himself watching over Juli's fragile mental state while keeping his own feelings for Juli under wraps. Then new student Eric enters the school - and he has an uncanny resemblance to the deceased Thomas... 

*Originally serialized in 33 chapters in Shuukan Shoujo Comic.

Chapter count includes 7 oneshots:

-   Senbonme no Pin (千本目のピン); Bessatsu Shoujo Comic Oshougatsu Zoukan Flower Comic 1973
-   Johnny Walker-kun no Bara Monogatari (ジョニーウォーカーくんのバラのものがたり); Bessatsu Shoujo Comic Ciao 1973-11
-   Bianca (ビアンカ); Shuukan Shoujo Friend Zoukangou 1970-07-07
-   Sayo no Nuu Yukata (小夜の縫うゆかた); Shuukan Shoujo Comic Natsu no Zoukan 1971
-   Aki no Tabi (秋の旅); Bessatsu Shoujo Comic 1971-10
-   Shiroi Tori ni Natta Shoujo (白い鳥になった少女); Bessatsu Shoujo Comic 1971-12
-   Mitsukuni no Musume (みつくにの娘); Bessatsu Shoujo Comic Oshougatsu Zoukan 1972*

1. **Houmonsha** (訪問者)
2. **Shiro** (城)
3. **Niseou** (偽王)

The title story features the earlier life of the character Oscar from the manga "Thomas' Heart." Due to many large and small problems that have added up over the years, Oscar's parents' marriage is collapsing. One day, after a fight that Oscar believes is going to end like all of the others, his father does something irreversible. Now Oscar and his father will have to deal with the consequences.

(Source: MangaHelpers) 

*Notes:*
\- Includes the one-shot Shiro (城)
\- Includes the one-shot Egg Stand (エッグ・スタンド)
\- Includes the one-shot "Tenshi no Gitai (天使の擬態; Angel Mimic)"