Ossan ga Bijo. 1 "Warumono" wo Hajimeyou!
| Volume Title | Ossan ga Bijo. 1 "Warumono" wo Hajimeyou! |
| Japanese Volume Title | おっさんがびじょ。1 “わるもの"を始めよう! |
| Light Novel | Ossan ga Bijo. |
| Publisher | EARTH STAR Entertainment |
| Light Novel Label | Earth Star Novel |
| Author | Maru Yamada |
| Illustrator | Kaori Fujita |
| Target Readership | Male |
| Volume | 1 |
| Release Date | January 15, 2015 |
| Pages | 342 |
| ISBN-10 | 4803006601 |
| ISBN-13 | 978-4803006605 |
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