Hi Susiesan, I made some changes to your itinerary. I eliminate Malang/batu from your trip. There's not a lot to see there. Probably some tea plantation. Malang/Batu is just one of city in high elevation ground which usually local people like to go for relaxing and escape the heat. I think Sarangan is much better place to visit than Batu.

Trip B: Bali – Java Island
Day 6 Bali - pick up at the hotel in Bali and drive to Ketapang in Java Island.
Day 7 Kepatang – Take Jeep to Ijen for Ijen Crater Trekking (3/3 KM one way)
Day 8 Ketapang – Watu Ulo beach, Sukamade beach
Day 9 Sukamade – Bromo
Day 10 Bromo - Madakaripura waterfalls - Sarangan lake
Day 11 Sarangan lake
Day 12 Sarangan lake - Solo
Day 13 Solo – Borobudur
Day 14 Borobudur – Yogyakarta
Day 15 Yogyakarta
Day 16 Yogyakarta – Fly to Jakarta – Connecting JL to Tokyo

Day 10 will be your longest trips, you'll most likely arrive at midnight at Sarangan lake, thus Day 11 will help you recuperate while you enjoy the lake and mountain sight. Lava view Bromo was the best hotel in bromo 2 years ago when I went there.