Perhaps next to Japan, there have been several countries like Hong Kong (before it was subsumed by China), Taiwan, and France which have interesting developments in their importation of manga mainly because these countries have a history of local publishers, whether legally or illegally, translate various titles into the lingua franca. The Philippines's key position in Southeast Asia appears to make it ideal for the assimilation of such culture but that wasn't the case. In many ways, the growth of anime in the country surpassed the growth of local manga, at least those translated into either English or Tagalog.
For the most part, the Philippines has always imported their manga from other countries. While there were some importation of authentic manga from Japan, in the 80's and early 90's, most manga titles like the popular Dragonball were coming from Taiwan and translated into traditional Chinese. In many ways, manga wasn't really accessible, unless you were familiar with either Japanese or Chinese, or settled for looking at the pretty pictures.
In my opinion, the English manga boom began in the 90's, at the time US publishers started translating manga into English. Those same titles trickled into the country via comic stores and a dedicated few bought those titles, mainly because of the expensive price point. The most well-known title at the time was Viz's Ranma 1/2. (For a more comprehensive history, you can read my previous essay On the US Manga Phenomenon.) In many ways, the US manga industry ran parallel with the Philippines. When the first English anthology manga magazines like Mixxzine and later Animerica Extra (Viz's first attempt and would be succeeded by the more popular Shonen Jump) popped up in the US, they also found its way into our shores (and in fact one of the contributors for Animerica was Johann Chua, a Filipino SF&F fan).
For quite some time, a good source of English manga was solely the domain of comic stores. There was a brief period when online scanlations were pirated: they were printed on cheap paper and then sold to the masses. Local laws were not so stringent (or perhaps merely ignorant) so the pirates were able to peddle such material in legitimate shops (whether bookstores or magazine stands). In the long run though, I don't think the pirates thrived (or perhaps they simply made a small killing) and now they've disappeared.
If the 90's was grass-roots growth, 2000 onwards was marked with interesting developments. Somebody on the side of distribution discovered that Viz's license extended only to the US (and a few other countries). For some years, importation of Viz-translated manga into the Philippines ceased (and making existing stock such as copies of Nausicaa valuable), at least when it came to the comic shops. Two big US publishers also tried to dabble in the manga industry. One was Time-Warner, who owns DC Comics (who in turn owns Wildstorm Press), and they released a manga imprint called CMX. This was significant because at the time, Time-Warner was striking deals with local bookstores, and a huge influx of graphic novels made its way into local bookstore shelves. These would later include the CMX line. The other as Del Rey, popularly known for its line of SF&F authors like Terry Brooks. They forayed into the manga business and again, many of their titles found its way to local bookstore shelves. This marked an interesting time in the manga industry because comic shops stopped being the only place you could purchase comics.
The Philippines would not be left in the dark. Summit Media, local publisher of best-selling magazine FHM, would try their hand at publishing manga. One title that they released and was no surprise to me was Ragnarok Online, cashing in on the MMORPG's popularity at the time. There were copies of Tokyopop's translation but Summit Media sold theirs for a third of the former's price and distributed it not just to comic shops and bookstores but to magazine stands. The other title they imported, which was baffling, was Slam Dunk, a basketball title that was popular in the 90's. Perhaps worthy to note was where the translations of these titles came from: Singapore. So if the English was less than perfect for either title, now you know the reason. Eventually though, Summit stopped distributing manga. Why? According to the rumors, while both titles sold quite well (more of Ragnarok Online than Slam Dunk), it wasn't at the quantity that the publisher was hoping for. And in many ways, you do need to sell huge quantities to be selling it at their price point. Another title I saw on the local shelves was English Beyblade manga, at the time when Beyblade was the biggest craze in town. Aside from these exceptions, manga remained in the domain of US imports.
Currently, there's been a juxtaposition when it comes to Viz and Dark Horse manga. The distributor is finding it difficult to import the latter more than the former (and the former is trickling its way into mainstream comic retailers and bookstores). One interesting phenomenon however is how the local bookstores got into the manga business. If comic retailers had problems importing certain titles from specific publishers, bookstores weren't as limited. I could cite independent bookstore A Different Bookstore importing Rurouni Kenshin and Yu-Gi-Oh! manga from Viz but the biggest development was Fully Booked importing huge stocks of manga. First they began with Tokyopop titles back when Fully Booked was still known as Page One but now they're acquiring everything from Dark Horse to Viz.
Just recently though, there have been interesting developments. Fully Booked for example has expanded its selection. Rather than simply importing manga from the US, they've started to tap into the Singaporean line and selling such titles for half the price of their US counterparts. Other bookstores on the other hand stock titles from Time-Warner, Del Rey, and Vertical. New comic shops like Comic Odyssey seem to be able to import Dark Horse titles and Viz titles, and they do have a veritable selection rivaling that of Fully Booked (albeit in less quantities). What's interesting for me however is how veteran comic shop Comic Quest is doing. While not having a diverse mainstream selection, they are stocking titles which you'll probably never see on bookstore shelves: yaoi and boy's love titles that aren't being carried by giant publishers (i.e. Time-Warner and Tokyopop) such as Only the Ring Finger Knows.