Harumi Triton Square, where Sumitomo Corporation's Tokyo Headquarters are located, undertakes a variety of measures aimed at making the Triton Square "town" eco-friendly. Harumi Corporation, an affiliate of Sumitomo Corporation, hosted the Fourth Environmental Exhibition from July 29 to 31, 2009 in the second floor Grand Lobby of Triton Square. Diverse environmental exhibits were on display at the venue, and included: the winner of the first Robot of the Year Grand Prize, Cleaning Robot, which automatically moves around buildings, cleaning the floors overnight; as well as display panels on ecological banana cultivation.

During the exhibition, tours were held of the central control facilities (located on the third and fourth basement floors of Triton Square), which implement integrated control of: power receiving/transforming, water supply, waste water discharge, and air conditioning for the entire "town." A highly energy-efficient heat-source system, the Triton Model, which attracts worldwide attention, was also displayed. The system is the most energy efficient of its kind, simultaneously producing cold and hot water with its heat pump, which is used for air-conditioning by capitalizing on atmospheric heat. Most of the energy used for air-conditioning during the day is drawn from the energy accumulated at night in a large heat storage tank, making use of midnight electric power discount, which allows for efficient, energy-saving operations. One Triton Square office worker, taking part in the tour, remarked with surprise, "I never knew that the building I worked in was equipped with such an eco-friendly system!"

The Triton Square "town" boasts a large, green area of 6,600 square meters in total, filled with a variety of plants. While the flowers and plants that grow throughout the year decrease land surface temperatures and alleviate heat-island effects, the planted area also serves as a welcoming place for people to relax. Takashi Yamazaki, President of Harumi Corporation, which manages the "town," says, "We are determined to continue striving toward an eco-friendly "town," in which housing, commercial facilities, and offices respectively are in harmony with the environment.