Cross Over is a Japanese manga written an illustrated by Kouji Seo. The series primarily follows the St. Mariannu boy's basketball team led by the freshman Ogata Natsuki to defeat the prefecture's best team, Fujiwara Academy. This story takes place in the same universe as other Kouji Seo's works do: Suzuka and A Town Where You Live.
Ogata Natsuki loves to play the sport of basketball. His passion for the game and his effort compensates his short stature. Encouraged by his Junior High teammates to tryout for the top High School basketball team, Fujiwara Academy. After his tryout, he meets Tachibana Mitsuki who is St. Mariannu High School's basketball team's manager. Ogata goes to watch St. Mariannu 's exhibition game against Fujiwara Academy. After an injury of St. Mariannu player, he decides to substituted in for the player so the game can continue. Afterwards he finds out that he made the team for Fujiwara Academy by their coach. After seeing the difference in sportsmanship between the teams, Ogata decides to attend St. Mariannu and try to help them defeat Fujiwara Academy.
St. Mariannu High School
- A coeducational high school that is known for their cheerleaders squad that had won national three years in a row. The school normally has a weak basketball team because the good players go to Fujiwara Academy, which is close by.
- Ogata Natsuki - He is a freshman small forward, who is relatively short, being only 159 cm (about 5'2'') tall. This is made up by the fact that he is fast, skilled, and is determined to win. He can be thought of as obsessed with basketball and therefore dense to other things. He often impresses people with his speed and skill. Ogata sometimes hides his true feelings, so that he doesn't have others worry about him. Ogata states that he declined his acceptance to Fujiwara because he rather defeat a strong team than play on one. Ogata lives with his aunt and is often caught peeking at the cheerleeding squad when they bathe, but unlike Katayama, it is on accident.
- Katayama Eiji - He is a freshman, who plays the position of center. He only plays this position because he is the tallest on the team and would prefer to play shooting guard. He is highly competitive with Ogata on and off the court. Katayama is known as a pervert, often peeking at the cheerleeding squad when they bathe and flirting with them and the manager. In America he was considered a genius shotting guard and a trickster. He used to attend Houtei High and was a starter for their basketball team but later left the team after Chris was kicked off the team.
- Christopher Knight - He is a freshman Power Forward/Center, who is American. He is very tall and great shot blocker until he injured Kain. Along with Katayama, they were starters in America but was later kicked off the Houtei High team for refusing to jump. He refuses to jump because him jumping was the reason Cain was injured, though he later starts to jump again thanks to Ogata. He decided to join Katayama at Mariannu High.
- Toude Higushide - He is a senior point guard and the captain of the basketball team. He often scouts their competition and comes up with the team's strategies. He often helps out the Nanba and Umeda during practice who are less experienced then the other players. Toude is considered a weak captain because can't be strict and controlling.
- Nakajima - He is a senior power forward, who is sensitive about his forehead. He often practices fast break drills with Ogata and Katayama. In the beginning he refuses to play or accept Christopher but later they get along and become friends.
- Nanba - He is a freshman shooting guard, who lacked self-confidence and often made excuses for not making the extra effort when he played sports. Inspired by Ogata, he is determined to change this part of himself.
- Umeda - He is a freshman shooting guard, who is much like Nanba, lacks self-confidence.
- Tachibana Mitsuki - She is the sophomore manger of the basketball team. She is friends with the cheerleaders, but when asked to join them she claims that she is too slow. She cares greatly about the basketball team and goes as far as making bentos for Ogata and Katayama so that they eat healthy. She often worries about Ogata.
- Usesugi - She has the most reserved personality of the cheerleaders. Being the leader of the squad, she gets annoyed if people are looking down on her school. She has a crush on Toude and often lends her advice to him.
- Miki Shibata - She takes the role of enforcer of the cheerleading squad against boys' perverted actions and severely punishes them, especially Katayama. When excited by watching good games, she often bear hugs Ayumi.
- Carie - She is an Eurasian and has spent time in the US cheerleading but had to go to Japan for Highschool. Ari worries about Christopher after seeing how much he has changed since they met in America. She is also the older sister of Cain whom she cares deeply for. She is very sociable and seem to follow basketball in which she likes to root for the black sheep teams.
- Asakura Moe - She is a shyest of the cheerleaders and has an crush with Ogata. She tried to confess to Ogata but after a series of bad events, she decided not to tell him yet. She is easily saddened when seeing Ogata with Mitsuki, but she decides not to tell anyone.
- Ayumi - She has childlike personality of the cheerleaders. She often is at the mercy of Miki when she gets excited during game.
- Fujiwara Coach - He's very demanding of his players and does not tolerate failure of meeting his expectations.
- Kitsukawa Kyouichi - Fujiwara's team captain and the senior point guard. He is consider by the fans to be the best basketball player in Japan. He often tries to help Maeda realize the difference between him and Ogata.
- Arai Kazuki - Fujiwara's shooting guard and is known for his shooting ability.
- Maeda Hayato - Fujiwara's freshman point guard, who was personally recruited by their coach. He is similar to Ogata in many ways such as height, speed, and skill. They differ in their playing style, which Maeda plays a calculated game and Ogata plays with passion. Since Ogata and himself had the same opportunity, he is curious why Ogata made a different decision than himself.
- Mayor Yamano Hatari - A big supporter of the best sport teams in his city. He even set up a basketball tournament to showcase the Fujiwara Academy basketball team. At first he does not like the St. Mariannu basketball team, but after seeing how good they are he decides to help them out by setting up a training camp for St. Mariannu basketball team and cheerleader squad.
- Amamiya Shizue - The Mayor Hatari's secretary. She is very professional about her job and very little upsets her.
- Mr. Sanadai - A lazy ancient martial arts master, who was St. Mariannu basketball training camp coach, even though he knows nothing about basketball. By incorporating his martial arts, St. Mariannu learned to increase their speed and stamina.
- Kain - Ari's younger brother. In the past when Christopher was still in America, Kain begged Christopher to teach him basketball after hearing how good he was from Ari. Christopher agreed to teach him, but during practice Christopher jumped to block the ball and accidentally collided with Kain, severely injuring him. Since Kain's injury he has acted like he hated Christopher but still sees him as his hero and forgives him.
- Miyanaga - After Katayama left the Houtei basketball team, Miyanaga became Houtei's ace shooting guard. He hates Katayama. Miyanaga can see through most of Katayama's tricks, but he still finds himself losing to him.
</td></tr><tr style="text-align: center;"><td id="vol2">2</td></td><td> November 15, 2002</td><td>ISBN 978-4-06-363172-2 </td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">
</td></tr><tr style="text-align: center;"><td id="vol3">3</td></td><td> January 17, 2003</td><td>ISBN 978-4-06-363197-5 </td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">
</td></tr><tr style="text-align: center;"><td id="vol4">4</td></td><td> March 17, 2003</td><td>ISBN 978-4-06-363220-0 </td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">
</td></tr><tr style="text-align: center;"><td id="vol5">5</td></td><td> May 16, 2003</td><td>ISBN 978-4-06-363237-8</td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">
</td></tr><tr style="text-align: center;"><td id="vol6">6</td></td><td> August 12, 2003</td><td>ISBN 978-4-06-363275-0 </td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">
</td></tr><tr style="text-align: center;"><td id="vol7">7</td></td><td> October 17, 2003</td><td>ISBN 978-4-06-363301-6 </td></tr><tr style="vertical-align: top; border-bottom: 3px solid #BDB76B;"><td colspan="3">