H-IIA

From Wikipedia:
H-IIA (H-2A) is an active expendable launch system operated by Mitsubishi Heavy Industries (MHI) for the Japan Aerospace Exploration Agency. These liquid fuel rockets have been used to launch satellites into geostationary orbit; lunar orbiting spacecraft; Akatsuki, which studied the planet Venus; and the Emirates Mars Mission, which was launched to Mars in July 2020. Launches occur at the Tanegashima Space Center. The H-IIA first flew in 2001. As of December 2021, H-IIA rockets were launched 45 times, including 39 consecutive missions without a failure, dating back to 29 November 2003.

Shown here is the H-IIA in its H2A-202 variant, the only active version of the H-IIA family

In-game pictures:

Important Notes:

(a) Do NOT oversteer the rocket. Start off with a pitch of 75° and wait until the SRBs fall off. Then only you can lower the pitch progressively.
(b) Shut down the 1st stage engine when the fuel reaches about 30%. The second stage can make up for it.
(c) Fairings jettisons smoother when engines are not ignited.

Final Notes:

I am 100% sure that there are some flaws in the build (1st stage engine compartment). Hence, do not expect it to perform perfectly. The craft was only tested in the stock system and i do not think it is suitable for RSS (test it if you want!). Hopefully you enjoyed this build and would consider supporting me! on my future builds!