2008 Tomy Trains?

Biggest sets? Might be right, there is also a 7423 Super Deluxe Set. Also there is this Japanese set that was mentioned in the Phantom Gems of Plarail section of the museum: "The Big Layout"

I will also include the breakdown of The Big Layout Japanese set, taken from the museum:

車両：２スピード新幹線、ライト付Ｄ５１
レール：直線レール５セット、１／２直線レール１セット、曲線レール５セット、ストップレール１セット、ターンアウトレール４セット、単線複線ポイントレール１セット、自動ポイントレール１セット、坂曲線レール２セット
ストラクチャー：トンネル１セット、ブロックトンネル１セット、大鉄橋１セット、洗車場１セット、ブロックはしげた３セット、
複線踏切１セット、パネルステーション２セット、自動発車駅１セット、単架線１２コ、複架線３コ、信号２本、立木６本、吊り橋３セット

Translation:

Content breakdown:

Vehicle: 2-speed Shinkansen, D51 with light
Rails: 5 sets of straight rails, 1 set of 1/2 straight rail, 5 sets of curved rails, 1 set of stop rails, 4 sets of turnout rails,
1 set of single track to double track point rails, 1 set of automatic point rail, 2 sets of slope curve rail.
Scene Parts: 1 set of tunnels, 1 set of block tunnels, 1 set of big iron bridge, 1 set of car wash, 3 sets of block piers,
1 set of double-track crossing, 2 sets of panel station, 1 set of automatic departure station, 12 sets of single track overhead line, 3 sets of double track overhead line, 2 signals, 6 standing trees, 3 sets of white suspension bridge

These "sets" are relating to the products that entered commercialisation with their original single item packaging.