|Japanese name:||一条 かれん|
Despite her strength she has a kind nature and is one of the more timid girls in 2-C. She is in love with Imadori, but gets embarrassed when this is hinted at. Imadori also initially avoids her, not only because of her small measures (later it is revealed that she does have considerably large breasts), but also because he fears her strength. She is also a good singer, and her singing is featured in episodes 2 and 6 of School Rumble - Second Term.
When Imadori met her practicing wrestling and asked her why she liked it, she said that she really did not want to do wrestling. Later, when Imadori, along with Harima and Hanai were working for a moving company, they found out that Ichijō was also working with them as well as how strong she was. At the end of their shift, Imadori accidentally said that he could take Karen out on a date with his earnings, which Karen agrees to, even though Imadori did not really mean it.