Lentz is a second Lieutenant of the Black Knights. He is extremely loyal to their cause, willing to commit even the most dishounorable acts in their name (unlike his counterpart, second Lieutenant Schneider). He is bigoted and looks down upon Japanese, often referring to them as monkeys. He is very skilled and powerful though, as he is able to break through a hold set on him by a former high-ranking member of the Sanada Ninja clan, named Kaita and leave him badly injured afterwards (although he is later saved by Tsukayama Yutarou's medical expertise).

Later on, under orders from First Lieutenant Meldars he surprise attacks Misanagi, and inflicts a deep shoulder cut on her, despite the fact that she was helping the Black Knights locate the Divine Elixir. However, Schneider rescues Misanagi and breaks Lentz' battle axe with his sword. Schneider is then forced to deal with Meldars, but proves no match for him.

Afterwards, as Himura Kenshin and his crew arrive, Lentz battles Myōjin Yahiko and Yutaro and easily defeats them. Kaita rescues the two children and easily defeats Lentz this time around breaking his sword in two using a Wakizashi (small Japanese blade), despite being unable to use his right arm as a result of Lentz' assault on him in their first battle. Kaita saves Lentz' life after rendering him unconscious.

After the battle, Schneider and Lentz both turn themselves in to the Germany embassy in Japan.
(Source: Rurouni Kenshin Wikia)