(真井 德次郎) Edo era professional, fl. 1840s. A member of the Honinbo school, he played ten times against Shusaku between 1843 and 1845, during which time he was 4d.
Jisho also gives the readings Sanei and Shin'i for the family name 真井, which might be a cause of confusion. He may also be better known under another name.