| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Bijinesu De Tsukaikonasu Nyūmon Teiryō Bunseki: Ishi Ketteiryoku O Takameru Sukiru | 978-4-534-04419-8 (4-534-04419-4) | 2008 |
| Bijinesu De Tsukaikonasu Nyūmon Teisei Bunseki: Mittsu No Shikō O Tsukaiwake Kumiawaseru | 978-4-534-04566-9 (4-534-04566-2) | 2009 |