Historical Western contact with Japan didn't exist until the Portuguese traveled there directly through sea in 1542 (at Tagenashima). They didn't even know about Japan's existance until a few years later they arrived directly to China in 1513 (periphery) and mainland in 1517 (Guangzhou). This was part from a serie of explorations and discoveries made by the Portuguese starting a century earlier and ending with the arrival to Tagenashima.

With that said, it would take a few decades to the Portuguese to develop the logistics required in each place to develop a trading market (of handcraft goods, species, raw materials and at a later point also slaves, exchanges made often in silver, but also in gold), which included conquering undefended ports or making new ones. We really can't talk about Westerners traveling with a decided destination to Japan until the second half of the 16th century. Since the voyage would easily take half a decade, then only merchants looking for wealth, ambassors defining the political frameworks and people from the churchs made the travel.

Only Portugal had a travel route to Japan during the 16th century, so you had to know Portuguesse or at least be familiar with its basics to travel (and also have the correct contacts to get in the ship), unless you were sent by the church, by which intance you might have been sent with a translator or workaround with your Latin to communicate around (in any case you were bound to learn some Portuguesse during the travel). Your ship would travel around the coasts of Africa, the Middle East, South Asia and finally China before your travel to Japan, you will be landing at different ports for supplies, trading goods from other places and European ones for a profit, and buying your supplies with gold and silver. Those ports are mostly Portuguese controlled so you can expect to trade with a fellow Portuguese merchant, or in the worst case a local familiar with the Portuguese and the basics of their language, or you can know a Portuguese who might be familiar with the local language to act as intermediary.

Once you arrive to Japan, well, you do your thing. If you're a missionary, you gotta do local research and learn the language, then begin to convert people to Christianism in whever approach you can think of (which was often also a process of "westernizing" them). If you're a merchant you must have your Japanese intermediary contacts to work around, selling whatever American, Asian, African and European goods that wasn't sold before for Japanese ones (or just get a silver profit) in shops established near the coasts. If you are an ambassador then you're likely to be taken directly to the Shogun and speak with an intermediary for whever reason you were sent there which would then talk to the Shogun itself.

During the early 17th century a few other European powers would begin to stablish direct trade routes to Asia (often using the Portuguese Ports or neutral ones), including Japan, being the Dutch the ones who would put more effort into the Japanese market. Japan fearing christanization (and westernization), alongside other motives, began a policy of isolation from the West starting in 1639, where Europeans were forbidden to enter Japan proper and all traders were forbidden with the exception of the Dutch, which were allowed to operate exclusively at the periphery of Japan at the enclave of Dejima. They weren't allowed to enter somewhere else in Japan aside than at Dejima for trading, aside a short anual visit to the Shogun at Edo. Japanese intellectuals would gain an interest in Western sciences and technology and plenty would begin to learn Dutch to afterwards translate the traded books to Japanese, this period called Rangaku helped to pave the way for a succesful industrial revolution two centuries later in Japan, when Japan ended its isolation in 1853.

For travels before the second half of the 16h century, we just don't know. There are not historical accounts describing Europeans in Japan before that neither. For instance you can't travel to a place you don't even know it exists and very few Europeans traveled to China to start with. The period were most Europeans traveled to China was during the peak of the Mongol Empire in the late 13th and early 14th centuries, were most Asia was politically unified by the Mongols, so as long as you gained the favor of a mongol court (which can be either through intermediaries or you learning their language), you would travel through most Asia well into China through the silk (land) route and doing your trades and things using mongol intermediaries (or most often, working in the mongol court itself, like Marco Polo did).

Before and after (at least until the 16th century) the Mongol Empire it was nearly impossible to make the travel to East Asia because more often than not a kingdom in the middle way would stop you, or the route was unprotected enough from bandits that everyone would advise you to not continue without proper know-hows of the zone. West-East trade was done thorugh a serie of intermediaries (mostly Muslims, using Arab or Persian to communicate), each one receiving part of the profit.

This was the only reason why the Portuguese and later the Spanish decided to embark in their worldwide seafaring explorations in the first place, to get into the trading game of richies (BIG trading profits!) with the East, circumvating Muslim traders. Incidentally it was also for this that the Americas were discovered (they just tried traveling the other way to Asia).