JOOY-DTV (channel 4), branded as Mainichi Broadcasting System (Japanese: 毎日放送, Hepburn: Mainichi Hōsō; MBS) (formerly known as Mainichi Broadcasting System Television from 1959 to 2011), is a Japanese television station serving as the Kansai region key station of the Japan News Network, owned-and-operated by Mainichi Broadcasting System, Inc. a subsidiary of MBS Media Holdings with its studios being based in the Kita-ku ward of Osaka.

From its sign on in 1959 to 2021, MBS operated as a unified broadcaster, with its radio and television operations being intact until 2017 when a major restructuring caused the operations to be held under the second incarnation of MBS. In 2021, the radio division was spun-off as a separate wholly owned subsidiary.

MBS is a core station of the Japan News Network (JNN), with TBS TV as its key station. MBS is a member of the "Five Company Federation" (comprising it, TBS, HBC, CBC and RKB) and is also a major shareholder of TBS Holdings. It distributes G-Guide EPG data, and used to distribute analog G-Guide program data to Tokushima Prefecture, where the only commercial TV station is affiliated to NNN/NNS.

During the 16 years and one month from the start of TV broadcasting until the network affair was resolved, it was a key station of NET (now TV Asahi) and was subsequently affiliated to the All-Nippon News Network (ANN) upon its opening. At the same time, Tokyo Channel 12 (currently TV Tokyo) was also connected to the station.

With the complete transition to digital terrestrial broadcasting on July 24, 2011, the notation of newspapers and TV information magazines on the same date changed from "Mainichi TV" (or "Mainichi"), which has been used since the start of television broadcasting), to "MBS TV" (or "MBS"). In the terrestrial digital TV G-Guide, it is written as "MBS Mainichi Broadcasting". Until July 23, 2011, the general name was Mainichi Broadcasting Television , and when it was simply called MBS, in the analog era, it was written as Mainichi TV in the radio and television columns of newspapers.

On April 1, 2017, the trade name was changed to "MBS Media Holdings", and both TV and radio broadcasting businesses were taken over by "(New) Mainichi Broadcasting". After that, on April 1, 2021, "MBS Radio Co., Ltd.", which was newly established as a wholly owned subsidiary of MBS Media Holdings, took over the radio broadcasting license and business that Mainichi Broadcasting had held, and moved exclusively to television (JOOR-DTV changed to JOOY-DTV).

Among the broadcasting stations in Osaka, the company, Asahi Broadcasting Television, and Kansai Television are three companies that opened earlier than their respective key stations in Tokyo (TBS Television, TV Asahi, Fuji Television). This is because these three companies and the three key stations had nothing to do with each other at the time of their establishment. However, despite being the oldest station in Japan to start radio broadcasting, it was the fourth station in Osaka to start TV broadcasting. It was almost the same time as Asahi (Nippon Educational Television (NET TV) at that time), but it was one month behind. On the other hand, Yomiuri TV and TV Osaka were established with the intention of their respective key stations, so they opened later than the key stations.

It has a strong connection with RKB Mainichi Broadcasting, co-produced and co-sold radio programs, and on television, even during the pre-1975 affair era, Kyushu Asahi Broadcasting (KBC) sold in-house programs that were not organized or sponsored net, and jointly established a health insurance union, and are presenting aspects of sister companies. In addition, the remote control key ID for analog master stations and digital broadcasting is also "4". It has a close relationship with Mitsubishi UFJ Bank and Resona Bank.