Seiji Tsutsumi (堤 清二, Tsutsumi Seiji, March 30, 1927 − November 25, 2013) was a Japanese businessperson, author and poet, also known by the pen names Takashi Tsujii (辻井 喬, Tsujii Takashi) and Ikuo Yokose (横瀬 郁夫, Yokose Ikuo).

[3]: 62  Misao wrote traditional Japanese poetry, which was Tsutsumi's initial introduction to writing.

[3]: 62 After receiving his degree in economics from the University of Tokyo in 1951, he re-enrolled as a literature student and worked as a secretary to his father.

[4] Following the death of his father in 1964, he led the spin-off of its logistics business to form the Saison Group, which eventually included the Seibu department stores, Seiyu supermarkets, Wave (a music shop), Parco (shopping complex), and the Muji and Loft variety store chains.

[6] Just before the death of his father Yasujiro, his brother Yoshiaki Tsutsumi was nominated as his heir, potentially due to Seiji's brief involvement with the Japanese Communist Party after the Second World War.