Spring-Summer champions

Known in Japanese as 春夏連続優勝 (haru-natsu renzoku yuusho) or Spring-Summer champions, this signifies the winning of both the senbatsu (Spring) and senshuken (Summer) tournaments in a calendar year. To date, this has been accomplished eight times:

Participation of overseas teams

Before World War II, teams from Taiwan, Korea, and Manchuria, which were all part of the Japanese Empire at the time, participated in the tournaments (in the spring only Taiwan took part). The first overseas teams to participate were Pusan Commercial School of Korea and Dalian Commercial School of Manchuria in the 1921 Summer Kōshien. Foreign teams have made it as far as the championship game, but have never won the tournament. The last tournament including foreign teams was the 1940 Spring Kōshien.

Six-time Kōshien participants

Currently, the maximum number of times a player can appear in Kōshien is five. However, under the former secondary school system, a player could appear more than five times. Here are two examples.

Makeshift Kōshien

The tournament was suspended due to the war from summer 1941 until spring 1946, with the exception of a "Promote the Fighting Spirit" tournament held by the Ministry of Education in 1942 at Kōshien. The number of teams was only 16 compared with 23 at the previous tournament, but each region held qualifying tournaments and sent teams to the national tournament. The military theme was prevalent at the tournament, with military slogans posted on the scoreboard, and traditional Japanese kanji characters replacing trendy English letters on the players' uniforms. The tournament proceeded smoothly and Tokushima Commercial (Tokushima) won the championship. However, since this tournament differed from past Summer Kōshiens hosted by Asahi Shimbun, it is not counted as an official Kōshien tournament.

Sacred "Dirt of Kōshien"

In the 1937 Summer Kōshien, Kumamoto Tech (Kumamoto) advanced to the championship game, but lost. After the game, Kumamoto Tech player Tetsuharu Kawakami grabbed a handful of dirt from the playing field of Kōshien Stadium and put it in his uniform pocket as a memento. Some years later, in the 1949 Summer Kōshien, after Kokura High (Fukuoka) lost to Kurashiki Tech (Okayama) in the semifinals, Kokura pitcher Kunio Fukushima scooped up some Kōshien dirt and took it home. This has become known as the original scooping of "the dirt of Kōshien" (甲子園の土, Kōshien no tsuchi). Since then, as a memento of their fleeting time on the hallowed grounds of Kōshien, players from the losing teams take home a pouch of the precious soil.

At the 1958 Summer Kōshien, Shuri High (Okinawa) became the first school to represent Okinawa (then under U.S. government rule) in a Kōshien tournament. They were eliminated in their first game by Tsuruga High (Fukui). After the game, they collected souvenirs of dirt and took them home. However, due to health regulations of the Ryūkyū government they were not allowed to keep the dirt, and it was confiscated. Some Japan Airlines flight attendants heard about this, and had a sea stone lying outside Kōshien Stadium sent to Shuri. Even today this "Monument of Friendship" lies in the yard of the school as a reminder of the first trip to Kōshien by a team from Okinawa.

Disqualifications

In the past, if a scandal was uncovered at a high school chosen to participate in the Kōshien, the school was forced to withdraw from competition in the tournament. A team's participation in the tournament was affected even by scandals not related to team members. However, recently, such unrelated incidents have had less effect on a team's participation.

Disqualifications from Kōshien based on circumstances other than scandals have also occurred. In the 1922 summer tournament, Niigata Commercial High School's disqualification was based on a star player's illness.

The Shirakawa Barrier and the Tsugaru Strait

For the first eight-plus decades of the Kōshien tournament, no team north of the Kantō region won a championship. This phenomenon became known in the high school baseball world as the Shirakawa Barrier after the actual fortification by that name, which was built near the border between the Kantō and Tōhoku regions in Shirakawa, Fukushima during the Nara Period (710–794).

At the 2004 Summer Kōshien, South Hokkaidō representative Komazawa University Tomakomai High (Komadai Tomakomai) took the title, and in one bound leaped over not only the Shirakawa Barrier but also the Tsugaru Strait separating Hokkaidō from Honshū. On the plane carrying the team and championship flag back home, at the moment the plane crossed the Tsugaru Strait, the passengers joined in unison for a celebration cheer.

Despite Komadai Tomakomai becoming the northernmost team to win a Kōshien championship, the championship flag did not actually pass through the Shirakawa Barrier on land, leading many fans (especially in the Tōhoku region) to consider the barrier unbroken. It was finally broken in 2022, when Sendai Ikuei (Miyagi) beat Shimonoseki Kokusai (Yamaguchi) to become the first Tōhoku school to win a Kōshien championship.

In 2005, Komadai Tomakomai won a second straight Summer Kōshien title, becoming the first to do so since Kokura Secondary (Fukuoka) in 1947–48. This title was tainted after the tournament, however, by reports of repeated incidents of physical punishment of one of the players, including once during the tournament, by the baseball club advisor (a 27-year-old school faculty member). Besides a reprimand for withholding the report until after the tournament, the High School Baseball Federation did not punish Komazawa Tomakomai. However, the report drew widespread attention to the issue of physical punishment in youth sports in Japan. It is believed that such physical punishment probably goes heavily underreported, due to cultural tendencies.

Passing Hakone and Fording the Tone River

In the early days of the Kōshien tournament, western Japanese teams won the majority of the tournaments and were thus seen as stronger than eastern teams. The metaphorical barrier keeping the championship flags in western Japan was Hakone, which, like Shirakawa, was a strategic checkpoint during the Edo period (1603–1868) requiring official passes to pass through.

Technically, the first "passing of Hakone" occurred when Keio Futsūbu (Tōkyō) won in the summer of 1916, the second Summer Kōshien. However, the tournament and high school baseball itself were far from the eventual heights of their popularity at the time, and 33 years passed before a Kantō team won another championship; that victory by Shōnan High (Kanagawa) in the summer of 1949 is regarded as the first passing of Hakone.

The first passing of Hakone in the spring was achieved in 1957 by Waseda Jitsugyō (Tōkyō), which was led by pitcher and future pro baseball legend Sadaharu Oh.

The championship flags made their way farther north into Kantō in 1962, when Sakushin Gakuin (Tochigi) became the first school to win both the Spring and Summer tournaments in one calendar year. To reach Tochigi, the flag had to "ford the Tone River," a major waterway that roughly divides the region into northern and southern halves.

Since then, Kantō teams have won championships more frequently, and as a result, these terms have fallen out of use.

Crossing the Kanmon Straits

Refers to a championship by a team from Kyūshū. The first team to "cross the Kanmon Straits" between Honshū and Kyūshū was Kokura Secondary in the 1947 Summer Kōshien. Coincidentally, Kokura Secondary repeated as champions in 1948, a feat not matched until Komadai Tomakomai did it in 2004 and 2005, also becoming the first team to bring the title to their region.

Passing Mount Aso

When a team from the southern half of Kyūshū wins a tournament, the championship flag must pass Mount Aso in Kumamoto. The first team to "pass Mount Aso" was Seiseikō High (Kumamoto) in the 1958 Spring Kōshien. This has not yet been achieved in the Summer Kōshien.

Crossing the ocean

When a team from Okinawa wins a tournament. The first to "cross the ocean" was Okinawa Shōgaku (Okinawa) in the spring of 1999. The first summer crossing occurred when Kōnan (Okinawa) won the 2010 Summer Kōshien.

Into snow country

When a team from the Hokuriku region wins a tournament. To date, no team has achieved this. Fukui Commercial High (Fukui) in the 1978 Spring Kōshien and Seiryō (Ishikawa, alma mater of Hideki Matsui) in the 1997 Summer Kōshien reached the semifinals. More recently, Nihon Bunri (Niigata, Niigata) reached the finals in 2009, and made an amazing comeback—down to their final strike with nobody on base in a 10–4 ballgame, they mounted a five-run rally and put the winning run on first base before finally succumbing, 10–9. Seiryō reached the finals in 2019, ultimately losing 5–3 to Riseisha (Osaka).