Given name: Jakub Family name: Zając

A merchant and owner of a big shop at Kosciuszki Street, the author's friend. An educated person, studying the Torah, loyal to Poland, a philanthropist, supplying with the income from the shop all sorts of undertakings aimed at helping the poor, a non-party. In November 1939 he lost his wife and two daughters as well as the house, shop and all money.

Chaim wrote that the existence of Jakub denied his opinion on the Polish Jews, which was not high. He called Jakub an exceptional men - one out of million - and devoted a lot of space in his diary.