Let's get the stats out of the way. Don't quote me on any of these, I will provide sources wherever I can but I am not confident the data is 100% accurate.
1. Tied for no. 11 - best-selling manga of all time.
https://en.wikipedia.org/wiki/List_of_best-selling_manga
2. 2nd best selling sports manga of all time - just behind Slam Dunk (I'm confident it would have been no.1 if the data was Japan-only)
3. One of the first manga (can be anywhere from first - fourth) to cross 100 million sales.
4. 1982 Shogakukan Award for Best Shonen Manga.
(Fun Fact: Mitsuru Adachi is tied with Naoki Urasawa for the most Shogakukans at 3 each)
https://en.wikipedia.org/wiki/Shogakukan_Manga_Award
5. Tied for no. 12 - most popular Japanese anime of all time by TV ratings with an average rating of 31.9 (That means 31.9% of all Japanese households on average watched Touch during air; for context One Piece averages ~7)
https://nendai-ryuukou.com/article/110.html
6. The most popular sports anime of all time by the above metric, closely followed by Ashita no Joe at 31.6
7. For at least 2 years (1985-87), 'Tatsuya' and 'Minami' were the most popular baby names in Japan.
8. The MIX adaptation (a time-skip sequel to Touch), despite being very mediocre, consistently traded places with One Piece for 5-7th on weekly TV ratings during it's run.
9. Still the most popular baseball manga in Japan after 40 years, though this isn't saying much.
https://en.gigazine.net/news/20100820_baseball_manga_top_10/
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That's an extremely impressive record, especially for something that many readers outside Japan have never heard of. But what the stats fail to describe is the impact it had - on the original readers, on the career of it's author, on baseball manga, on sports manga and most importantly, the Shonen 'pseudo-genre'. To understand that we need to go back in time to a time and place very different yet similar to ours - the period is the 80's, the country is Japan and the stage is, of-course, the action-packed Koshien.