2&3nd year of senior high school in japan

Hi there, so I want to write a story about some kids in japan ('cause I love Japan) but I don't know a lot of things about japanese 2&3nd year of senior high school and I want to confirm if what I know is correct so I will list some questions and I really want someone to answer them please
1. What time school starts and ends?
2. When (almost) exactly do the finals exams start and end in the 3rd trimester?
3.Same question as the previous one about the mid-terms exam and what are they?
4.Do they still have half-day school on saturday?
5.How is there scheduled planned? I mean how long is each class, when are their breaks and how long and many are they?
6.What can the kids do in the breaks?
7.What subjects do they have/take and how many times per week?
8.I know they have some school festivals during the year, how are they called and what are they basically?
9.Do they have lockers for their books (I know they have for their shoes)?
10.How many homerooms are in each school and how many students has each homeroom?
11.Where do they take their lanches (I know there is no cafeteria, or is there?)?
12.Do boys and girls have gym class together or they are divided by gender?
13.Do all the homerooms have gym together or they have each one individual?
14.Can you transfer to a different school in the middle of year or before the beginning of a new?
15.What is the 'classroom management tasks' and when does it take place?
16.I read somewhere that the students aren't allowed to go anywhere after school, before first returning home, does this rule still exist?
17.Can you only enter one after-school-club at a time?
18.How many times per week do the clubs meet and who chooses the days?
19.What is the most usual detention? (and other 'popular' kind)
20.When is the birthdate separation for each class year?
21.Do they change homerooms every year (mix classmates)?
22.Do they have team-asaingments in class? (the kind of that you have to meet to someone's place to do it)
23.What are the most-found facilities in school (exc. do they have swimming pools?)
24.What happens if a student is late for school?
25.How are the tests graded? (are they A,B or at 20,100etcetera?)
I am terribly sorry for the amount of questions and I really need someone to answer them and also to mention other important things I should know about japanese schools (for example, I know they have school uniforms and that the school year is April to March)
Thanks really a lot to whoever answers me :)

If you want to confirm what you know is correct, it would be better for you to write what you know rather than to ask what you don't know. It depends on the school or class, anyway.

Wow, that's a lot of questions but I'll take a stab at it. I've taught in 4 high schools in the past, so this is from my experiences. Note that it varies greatly between schools so the general answer to your questions is that it depends on the school.

1. What time school starts and ends?

Roughly 8:30 to 3:00

2. When (almost) exactly do the finals exams start and end in the 3rd trimester?

It varies a lot by the school. Generally they are around summer break and in March. 3rd graders have their last final exams earlier than the rest of the student, around the end of January.

3.Same question as the previous one about the mid-terms exam and what are they?

Roughly half way through the semester.

4.Do they still have half-day school on saturday?

Depends on the school.

5.How is there scheduled planned? I mean how long is each class, when are their breaks and how long and many are they?

About an hour for each class with an hour break for lunch.

6.What can the kids do in the breaks?

Eat lunch, visit their friends in other classrooms, etc. but they generally have to stay on school grounds.

7.What subjects do they have/take and how many times per week?

Depends on the school

8.I know they have some school festivals during the year, how are they called and what are they basically?

Most schools hold a school festival (bunkasai) once a year, every 2 years, or every 3 years. Some schools have additional festivals that are open to the public.

There are a number of other events like marathon taikai, ball sports day, yosenkai, but it depends on the school.

9.Do they have lockers for their books (I know they have for their shoes)?

yes

10.How many homerooms are in each school and how many students has each homeroom?

There are as many homerooms as are needed for the school population. There are usually between 30-40 kids per class.

11.Where do they take their lanches (I know there is no cafeteria, or is there?)?

Most kids ate in their homeroom, the hall, or other classrooms. Some schools have cafeterias.

12.Do boys and girls have gym class together or they are divided by gender?

At my schools the gym classes were by homeroom.

13.Do all the homerooms have gym together or they have each one individual?

Usually individually

14.Can you transfer to a different school in the middle of year or before the beginning of a new?

Yes

15.What is the 'classroom management tasks' and when does it take place?

I'm not sure what you are referring to by 'classroom management tasks'.

16.I read somewhere that the students aren't allowed to go anywhere after school, before first returning home, does this rule still exist?

No such rule existed at any school that I taught.

17.Can you only enter one after-school-club at a time?

It depends on the club. Sports teams are a big time commitment that are probably best done one at a time. Other clubs only meet once or twice a week, so you could be a member of several of those.

18.How many times per week do the clubs meet and who chooses the days?

See above. The days are chosen by the students, the teacher in charge of the club, or by the schedule if they need special facilities.

19.What is the most usual detention? (and other 'popular' kind)

My schools didn't have detention as it existed in my US high school. Occasionally kids would be disciplined by being yelled at in the teachers room.

20.When is the birthdate separation for each class year?

April 1st.

21.Do they change homerooms every year (mix classmates)?

Generally no, but it depends.

22.Do they have team-asaingments in class? (the kind of that you have to meet to someone's place to do it)

Yes, that is possible.

23.What are the most-found facilities in school (exc. do they have swimming pools?)

Probably a gym would be most common, followed by a baseball field. Most schools probably do not have a swimming pool.

24.What happens if a student is late for school?

They get in trouble with their homeroom teacher.

25.How are the tests graded? (are they A,B or at 20,100etcetera?)

Most of our tests were on a curved point system (typically out of 100 and then curved way lower). Letter grades were not used.

(for example, I know they have school uniforms and that the school year is April to March)

Not all schools require school uniforms, but most do.

I imagine it will be really hard to write believable story without youfve been actually experiencing thing like schooling in other countries.

But what I think you should know is that American ghomeroomh system doesnft apply in Japan. In Japan, teachers are the ones moving from room to room, and students stay in one room unless they need to use computer, science lab, music room, craft rooms and gym/field. Every room has a tan-nin (teacher in charge). Teachers also have their desks at teacherfs room, and thatfs where they usually stay since they have to move around during school hours.

Teachers also move up grades with you so they get to know their students better in those 3 years, and they keep the cycle every three years. Off course every now and then, some teachers change the grades to cover the transferred coworkers or to cover up some sort of mess that students usually donft know (like big complaints from parents). Students usually stay together specially on 2nd and 3rd grade of the high school years, since classes are already divided by specialized groups such as Science and Liberal Arts-focused.