16th Mar to Oct is 7 months. You are safe to travel.

If your passport validity is less than 6 months, KLIA immigration will ask you to fill up indemnity form that you understand your wish to travel out with the knowledge of under 6 months, and a risk of destination country rejecting you and put you on the next flight back.

I used the RM49 ASEAN for one week in HK and ID few times. No problem.

Either I subscribe at the last minute inside KLIA boarding gate. Or once I land latch on free Airport WiFi if available (enable WiFi only in flight mode) or until reach hotel to subscribe via Maxis App. Normally I do it at KLIA boarding gate to have immediate access when plane lands.

Once plane lands, switch off flight-mode as usual. Remember turn on mobile/cellular roaming (for call/sms). Then wait it search and connect to local telco. Receive SMS.

Check your Maxis roaming RM49/99 in Maxis app is activated to be safe. Then only turn on data roaming. Then I always screen-capture to have the date and time, to be safe in case Maxis charge me wrong later. So far never happen.

Sounds complicated but is seamless, no need poke here there, pull out sim card or scan e-sim. All apps in phone just work as usual.

Also you may not need to do in detail step as I mention, ie. just switch on call and data roaming. But I prefer to be step-by-step process.

Take note to ask when you check in at Penang or KLIA if your luggage will pass-through all the way to CTS.

If not, you may need to get out immigration & customs at Narita to pickup luggage (as International arrival) and then check in / drop luggage as domestic travel.

The last time I flew ANA KUL-NRT-CTS, at NRT after immigration, there are ANA staff who ask and divert our luggages automatically.

Things may have changed ...