Mannerheim is the director of a federal mental health facility secretly funded by the Union Corse, who experiments on violent criminals to observe the effects of the Banana Fish drug in the Banana Fish series.
He has light brown hair with his forehead visible and a same colored mustache.
He displayed fear when captured by Ash and called to Colonel Fox, to little avail, to help him.
Main Article: Mannerheim/Synopsis
With Golzine captured he comes to follow Fox's commands and complies with them to gather as many samples of Banana Fish as he can. Mannerheim is given his own armed escort to an escape helicopter under Fox's orders when Ash escapes. When captured by Ash, though Mannerheim calls to Fox for help he is shot dead by him despite his usefulness to the mercenary.
- Episode 14 Tender is the Night
- Episode 15 The Garden of Eden
- Episode 16 Lo, The Poor Peacock
- Episode 22 As I Lay Dying
- Episode 23 For Whom the Bell Tolls
- Episode 24 The Catcher in the Rye
Main Article: Mannerheim/Image Gallery
- In the chart of the correlation of Banana Fish's characters Dr. Mannerheim's chart as in the same case with Ash Lynx but unlike him, his chart being colorful (to mean alive) for the first post despite the fact that he was shot by Eduardo L. Fox. Until the decision was made of changing Ash's chart to be colored, Dr. Mannerheim's turns to be grayscale for the first step of changing the chart which means he died.