A new event invitation released by HTC has just surfaced online and it states that the occasion will take place in Hankone, Japan on Sept. 29.

The last time the Taiwanese smartphone maker announced an event for a possible new smartphone launch was last Sept. 6, which had already passed, and a lot of people had assumed that the rumored HTC One A9 or Aero would be introduced.

The A9 didn't make it to that event, so that only means it still isn't official. However, the new invite, which was written in Chinese, states that the event will be launching two flagship devices. The invite was taken from HTC's Weibo account and tweeted by tipster @upleaks.

Of course, HTC didn't specifically mention which devices will be unveiled; but recent leaks suggest that the two devices could probably be the HTC Aero 9 and Butterfly 3.

People who commented on the tweeted post are also hopeful that the two devices will be introduced.

According to rumors, HTC One A9/Aero will have a QHD display with 2560 x 1400 resolution and carry Corning Gorilla Glass 4.

There is no available report on just how wide the display will be but all speculations point to a 2.5D curved glass, just like those seen in Nexus 4 or iPhone 6, reports Android Pit.

A9 is also rumored to run on a Qualcomm Snapdragon 820 with either a 4 GB or 3 GB RAM, but the processor won't likely be available until next year; hence, A9 could possibly use the MediaTek Helio X20 ten-core processor.

On the other hand, the rumored Butterfly 3 could be an international variant of the HTC J Butterfly (HTV31), as reported in Gadgets NDTV.

It is said to run on Android 5.0 Lollipop and will have a 5.2-inch QHD display with 1440 x 2560 resolution. It is said to run on an octa-core Qualcomm Snapdragon 810 SoC with 3 GB RAM and an expandable 32 GB internal storage.