luggages in bus

can i carry large luggages in bus from mishima station to kawaguchiko station.

For highway bus,i never face any problem with my large luggage.But for local bus,i face problem with my large luggage,specially office hours,so i take taxy in peak hours

https://www.fujikyucitybus.com/highwaybus/kawaguchiko.html

This is the official statement of Fujikyu bus company.

大きな荷物（手回り品）については、バス床下のトランクをご利用いただけます。1人1個までとさせて頂いております。
下記を越える場合はお断りする場合がございます
1辺の長さが1メートル以内、容積0.027立方メートル以内、総重量10kgまで
お荷物のご予約は承ってございません。また、他のお客様のお荷物でトランクルームが一杯の場合、積み込めない場合もございます。その場合でも座席へのお持込は出来ません。ご了承ください。(ご利用予定の人数が多い場合等は全員分のお荷物を載せきれないケースもございます）。
大きなお荷物は、 事前に目的地の滞在先へお送り頂く事をお勧めいたします。
トランクからの荷物の出し入れは、お客様自身にお願いします。途中バス停で降車の場合はお忘れにならないようにご注意下さい。

Google translate:

For large luggage (personal items), you can use the trunk under the bus floor. Limited to one item per person.
We may refuse your request if it exceeds the following.
Length of one side within 1 meter, volume within 0.027 cubic meters, total weight up to 10 kg
We do not accept reservations for luggage. Also, if the luggage compartment is full with other passengers' luggage, you may not be able to load it. Even in that case, you will not be able to bring it to your seat. note that. (If there are many people planning to use the service, there may be cases where it is not possible to carry everyone's luggage.)
We recommend that you send large luggage to your destination accommodation in advance.
Passengers are responsible for loading and unloading their luggage from the trunk. Please be careful not to forget your ticket if you get off at a bus stop along the way.

Below is my opinion.

Ten years ago, most of the passengers were Japanese who tend not to have large luggages since most of us travel for short term (2-3 days). Now many foreign travelers are using this line and they bring many luggages hence this notice by Fujikyu bus.

I took a service going from kawaguchi to mishima today. My ticket came with the same disclaimer about 10kg luggage size.
However, many people had large luggage. My wife and i had 20kg luggage each. There was plenty of room and no one batted an eyelid. So i assume the disclaimer is there, just in case they actually fill up and cant take any more bags.