Short answers, pulled from the story.
Mainichi Broadcasting System began its first transmission on the 1st of March 1959 at exactly 10:00 a.m. from the summit of Mount Ikoma. This launch occurred four months after the station had originally planned to start in December 1958 due to corporate maneuvering involving Radio Tokyo TV.
Mainichi Broadcasting System switched its network allegiance from NET to the Japan News Network on the 19th of November 1974. The official transition to the new network took effect on the 1st of April 1975, allowing the station to break free from the constraints of its previous network and eventually secure top prime-time ratings.
Mainichi Broadcasting System established a North American branch in New York in 1962, making it the third Japanese television station to open a base in the United States. The station later became an associate member of the European Broadcasting Union in 1969 and formed agreements with major networks in the United States, Canada, West Germany, and France.
Mainichi Broadcasting System moved its physical operations to a new location in Chayamachi, Kita-ku, Osaka on the 1st of September 1990. The new facility included an open atrium on the first floor and the Galaxy Hall concert venue on the second floor, serving as the station's home for decades.
Mainichi Broadcasting System restructured into MBS Media Holdings on the 1st of April 2017, separating its radio and television operations. The radio division was spun off as a separate, wholly owned subsidiary on the 1st of April 2021, leaving the MBS entity as a sole television broadcaster.
Mainichi Broadcasting System won the triple crown of ratings from October 1975 to March 1980, securing the top spot in prime-time ratings for twenty-six consecutive weeks by the first half of 1978. This period of dominance resulted in revenue reaching 30.15 billion yen and profits of 5.12 billion yen.